{"id":1049,"date":"2017-01-10T23:49:19","date_gmt":"2017-01-10T23:49:19","guid":{"rendered":"https:\/\/courses.lumenlearning.com\/waymakermath4libarts\/?post_type=chapter&#038;p=1049"},"modified":"2019-05-30T15:46:55","modified_gmt":"2019-05-30T15:46:55","slug":"introduction-solving-problems-with-math","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/wmopen-mathforliberalarts\/chapter\/introduction-solving-problems-with-math\/","title":{"raw":"Solving Problems With Math","rendered":"Solving Problems With Math"},"content":{"raw":"<div class=\"textbox learning-objectives\">\r\n<h3>Learning Outcomes<\/h3>\r\n<ul>\r\n \t<li>Identify and apply a solution\u00a0pathway for multi-step problems<\/li>\r\n<\/ul>\r\n<\/div>\r\nIn this section we will bring together the mathematical tools we\u2019ve reviewed, and use them to approach more complex problems. In many problems, it is tempting to take the given information, plug it into whatever formulas you have handy, and hope that the result is what you were supposed to find. Chances are, this approach has served you well in other math classes.\r\n\r\nThis approach does not work well with real life problems, however. Read on to learn how to use a generalized problem solving approach to solve a wide variety of quantitative problems, including how taxes are calculated.\r\n<h2>Problem Solving and Estimating<\/h2>\r\nProblem solving is best approached by first starting at the end: identifying exactly what you are looking for. From there, you then work backwards, asking \u201cwhat information and procedures will I need to find this?\u201d Very few interesting questions can be answered in one mathematical step; often times you will need to chain together a <strong>solution pathway<\/strong>, a series of steps that will allow you to answer the question.\r\n<div class=\"textbox\">\r\n<h3>Problem Solving Process<\/h3>\r\n<ol>\r\n \t<li>Identify the question you\u2019re trying to answer.<\/li>\r\n \t<li>Work backwards, identifying the information you will need and the relationships you will use to answer that question.<\/li>\r\n \t<li>Continue working backwards, creating a solution pathway.<\/li>\r\n \t<li>If you are missing necessary information, look it up or estimate it. If you have unnecessary information, ignore it.<\/li>\r\n \t<li>Solve the problem, following your solution pathway.<\/li>\r\n<\/ol>\r\n<\/div>\r\nIn most problems we work, we will be approximating a solution, because we will not have perfect information. We will begin with a few examples where we will be able to approximate the solution using basic knowledge from our lives.\r\n\r\nIn the first example, we will need to think about time scales, we are asked to find how many times a heart beats in a year, but usually we measure heart rate in beats per minute.\r\n<div class=\"textbox exercises\">\r\n<h3>Examples<\/h3>\r\nHow many times does your heart beat in a year?\r\n[reveal-answer q=\"630883\"]Show Solution[\/reveal-answer]\r\n[hidden-answer a=\"630883\"]\r\n\r\nThis question is asking for the rate of heart beats per year. Since a year is a long time to measure heart beats for, if we knew the rate of heart beats per minute, we could scale that quantity up to a year. So the information we need to answer this question is heart beats per minute. This is something you can easily measure by counting your pulse while watching a clock for a minute.\r\n\r\nSuppose you count 80 beats in a minute. To convert this to beats per year:\r\n\r\n[latex]\\displaystyle\\frac{80\\text{ beats}}{1\\text{ minute}}\\cdot\\frac{60\\text{ minutes}}{1\\text{ hour}}\\cdot\\frac{24\\text{ hours}}{1\\text{ day}}\\cdot\\frac{365\\text{ days}}{1\\text{ year}}=42,048,000\\text{ beats per year}[\/latex]\r\n\r\n[\/hidden-answer]\r\n\r\n<\/div>\r\nThe technique that helped us solve the last problem was to get the number of heartbeats in a minute translated into the number of heartbeats in a year. Converting units from one to another, like minutes to years is a common tool for solving problems.\r\n\r\nIn the next example, we show how to infer the thickness of something too small to measure with every-day tools. Before precision instruments were widely available, scientists and engineers had to get creative with ways to measure either very small or very large things. Imagine how early astronomers inferred the distance to stars, or the circumference of the earth.\r\n<div class=\"textbox exercises\">\r\n<h3>Example<\/h3>\r\nHow thick is a single sheet of paper? How much does it weigh?\r\n[reveal-answer q=\"688739\"]Show Solution[\/reveal-answer]\r\n[hidden-answer a=\"688739\"]\r\n\r\nWhile you might have a sheet of paper handy, trying to measure it would be tricky. Instead we might imagine a stack of paper, and then scale the thickness and weight to a single sheet. If you\u2019ve ever bought paper for a printer or copier, you probably bought a ream, which contains 500 sheets. We could estimate that a ream of paper is about 2 inches thick and weighs about 5 pounds. Scaling these down,\r\n\r\n[latex]\\displaystyle\\frac{2\\text{ inches}}{\\text{ream}}\\cdot\\frac{1\\text{ ream}}{500\\text{ pages}}=0.004\\text{ inches per sheet}[\/latex]\r\n\r\n[latex]\\displaystyle\\frac{5\\text{ pounds}}{\\text{ream}}\\cdot\\frac{1\\text{ ream}}{500\\text{ pages}}=0.01\\text{ pounds per sheet, or }=0.16\\text{ ounces per sheet.}[\/latex]\r\n\r\n[\/hidden-answer]\r\n\r\nThe first two example questions in this set are examined in more detail here.\r\n\r\nhttps:\/\/youtu.be\/xF5BNEr0gjo\r\n\r\n<\/div>\r\nWe can infer a measurement by using scaling. \u00a0If 500 sheets of paper is two inches thick, then we could use proportional reasoning to infer the thickness of one sheet of paper.\r\n\r\n&nbsp;\r\n\r\nIn the next example, we use proportional reasoning to determine how many calories are in a mini muffin when you are given the amount of calories for a regular sized muffin.\r\n<div class=\"textbox exercises\">\r\n<h3>Example<\/h3>\r\nA recipe for zucchini muffins states that it yields 12 muffins, with 250 calories per muffin. You instead decide to make mini-muffins, and the recipe yields 20 muffins. If you eat 4, how many calories will you consume?\r\n[reveal-answer q=\"397938\"]Show Solution[\/reveal-answer]\r\n[hidden-answer a=\"397938\"]\r\n\r\nThere are several possible solution pathways to answer this question. We will explore one.\r\n\r\nTo answer the question of how many calories 4 mini-muffins will contain, we would want to know the number of calories in each mini-muffin. To find the calories in each mini-muffin, we could first find the total calories for the entire recipe, then divide it by the number of mini-muffins produced. To find the total calories for the recipe, we could multiply the calories per standard muffin by the number per muffin. Notice that this produces a multi-step solution pathway. It is often easier to solve a problem in small steps, rather than trying to find a way to jump directly from the given information to the solution.\r\n\r\nWe can now execute our plan:\r\n\r\n[latex]\\displaystyle{12}\\text{ muffins}\\cdot\\frac{250\\text{ calories}}{\\text{muffin}}=3000\\text{ calories for the whole recipe}[\/latex]\r\n\r\n[latex]\\displaystyle\\frac{3000\\text{ calories}}{20\\text{ mini-muffins}}=\\text{ gives }150\\text{ calories per mini-muffin}[\/latex]\r\n\r\n[latex]\\displaystyle4\\text{ mini-muffins}\\cdot\\frac{150\\text{ calories}}{\\text{mini-muffin}}=\\text{totals }600\\text{ calories consumed.}[\/latex]\r\n\r\n[\/hidden-answer]\r\n\r\nView the following video for more about the zucchini muffin problem.\r\n\r\nhttps:\/\/youtu.be\/NVCwFO-w2z4\r\n\r\n<\/div>\r\nWe have found that ratios are very helpful when we know some information but it is not in the right units, or parts to answer our question. Making comparisons mathematically often involves using ratios and proportions. For the last\r\n<div class=\"textbox exercises\">\r\n<h3>Example<\/h3>\r\nYou need to replace the boards on your deck. About how much will the materials cost?\r\n[reveal-answer q=\"36890\"]Show Solution[\/reveal-answer]\r\n[hidden-answer a=\"36890\"]\r\n\r\nThere are two approaches we could take to this problem: 1) estimate the number of boards we will need and find the cost per board, or 2) estimate the area of the deck and find the approximate cost per square foot for deck boards. We will take the latter approach.\r\n\r\nFor this solution pathway, we will be able to answer the question if we know the cost per square foot for decking boards and the square footage of the deck. To find the cost per square foot for decking boards, we could compute the area of a single board, and divide it into the cost for that board. We can compute the square footage of the deck using geometric formulas. So first we need information: the dimensions of the deck, and the cost and dimensions of a single deck board.\r\n\r\nSuppose that measuring the deck, it is rectangular, measuring 16 ft by 24 ft, for a total area of 384 ft<sup>2<\/sup>.\r\n\r\nFrom a visit to the local home store, you find that an 8 foot by 4 inch cedar deck board costs about $7.50. The area of this board, doing the necessary conversion from inches to feet, is:\r\n\r\n[latex]\\displaystyle{8}\\text{ feet}\\cdot4\\text{ inches}\\cdot\\frac{1\\text{ foot}}{12\\text{ inches}}=2.667\\text{ft}^2{.}[\/latex] The cost per square foot is then\u00a0[latex]\\displaystyle\\frac{\\$7.50}{2.667\\text{ft}^2}=\\$2.8125\\text{ per ft}^2{.}[\/latex]\r\n\r\nThis will allow us to estimate the material cost for the whole 384 ft<sup>2<\/sup> deck\r\n\r\n[latex]\\displaystyle\\$384\\text{ft}^2\\cdot\\frac{\\$2.8125}{\\text{ft}^2}=\\$1080\\text{ total cost.}[\/latex]\r\n\r\nOf course, this cost estimate assumes that there is no waste, which is rarely the case. It is common to add at least 10% to the cost estimate to account for waste.\r\n\r\n[\/hidden-answer]\r\n\r\nThis example is worked through in the following video.\r\n\r\nhttps:\/\/youtu.be\/adPGfeTy-Pc\r\n\r\n<\/div>\r\n&nbsp;\r\n<div class=\"textbox exercises\">\r\n<h3>Example<\/h3>\r\nIs it worth buying a Hyundai Sonata hybrid instead the regular Hyundai Sonata?\r\n[reveal-answer q=\"499109\"]Show Solution[\/reveal-answer]\r\n[hidden-answer a=\"499109\"]\r\n\r\nTo make this decision, we must first decide what our basis for comparison will be. For the purposes of this example, we\u2019ll focus on fuel and purchase costs, but environmental impacts and maintenance costs are other factors a buyer might consider.\r\n\r\nIt might be interesting to compare the cost of gas to run both cars for a year. To determine this, we will need to know the miles per gallon both cars get, as well as the number of miles we expect to drive in a year. From that information, we can find the number of gallons required from a year. Using the price of gas per gallon, we can find the running cost.\r\n\r\nFrom Hyundai\u2019s website, the 2013 Sonata will get 24 miles per gallon (mpg) in the city, and 35 mpg on the highway. The hybrid will get 35 mpg in the city, and 40 mpg on the highway.\r\n\r\nAn average driver drives about 12,000 miles a year. Suppose that you expect to drive about 75% of that in the city, so 9,000 city miles a year, and 3,000 highway miles a year.\r\n\r\nWe can then find the number of gallons each car would require for the year.\r\n\r\n<strong>Sonata:<\/strong> [latex]\\displaystyle{9000}\\text{ city miles}\\cdot\\frac{1\\text{ gallon}}{24\\text{ city miles}}+3000\\text{ highway miles}\\cdot\\frac{1\\text{ gallon}}{35\\text{ highway miles}}=460.7\\text{ gallons}[\/latex]\r\n\r\n<strong>Hybrid:<\/strong>\u00a0[latex]\\displaystyle{9000}\\text{ city miles}\\cdot\\frac{1\\text{ gallon}}{35\\text{ city miles}}+3000\\text{ highway miles}\\cdot\\frac{1\\text{ gallon}}{40\\text{ highway miles}}=332.1\\text{ gallons}[\/latex]\r\n\r\nIf gas in your area averages about $3.50 per gallon, we can use that to find the running cost:\r\n\r\n<strong>Sonata:<\/strong>\u00a0[latex]\\displaystyle{460.7}\\text{ gallons}\\cdot\\frac{\\$3.50}{\\text{gallon}}=\\$1612.45[\/latex]\r\n\r\n<strong>Hybrid:<\/strong> [latex]\\displaystyle{332.1}\\text{ gallons}\\cdot\\frac{\\$3.50}{\\text{gallon}}=\\$1162.35[\/latex]\r\n\r\nThe hybrid will save $450.10 a year. The gas costs for the hybrid are about [latex]\\displaystyle\\frac{\\$450.10}{\\$1612.45}[\/latex] = 0.279 = 27.9% lower than the costs for the standard Sonata.\r\n\r\nWhile both the absolute and relative comparisons are useful here, they still make it hard to answer the original question, since \u201cis it worth it\u201d implies there is some tradeoff for the gas savings. Indeed, the hybrid Sonata costs about $25,850, compared to the base model for the regular Sonata, at $20,895.\r\n\r\nTo better answer the \u201cis it worth it\u201d question, we might explore how long it will take the gas savings to make up for the additional initial cost. The hybrid costs $4965 more. With gas savings of $451.10 a year, it will take about 11 years for the gas savings to make up for the higher initial costs.\r\n\r\nWe can conclude that if you expect to own the car 11 years, the hybrid is indeed worth it. If you plan to own the car for less than 11 years, it may still be worth it, since the resale value of the hybrid may be higher, or for other non-monetary reasons. This is a case where math can help guide your decision, but it can\u2019t make it for you.\r\n\r\n[\/hidden-answer]\r\n\r\nThis question pulls together all the skills discussed previously on this page, as the video demonstration illustrates.\r\n\r\nhttps:\/\/youtu.be\/HXmc-EkOYJE\r\n\r\n<\/div>\r\n&nbsp;\r\n\r\n&nbsp;\r\n<div class=\"textbox key-takeaways\">\r\n<h3>Try It<\/h3>\r\n<iframe id=\"mom1\" class=\"resizable\" src=\"https:\/\/www.myopenmath.com\/multiembedq.php?id=17454&amp;theme=oea&amp;iframe_resize_id=mom1\" width=\"100%\" height=\"350\"><\/iframe>\r\n\r\n<hr \/>\r\n\r\n<iframe id=\"mom2\" class=\"resizable\" src=\"https:\/\/www.myopenmath.com\/multiembedq.php?id=17457&amp;theme=oea&amp;iframe_resize_id=mom2\" width=\"100%\" height=\"350\"><\/iframe>\r\n\r\n<hr \/>\r\n\r\n<iframe id=\"mom3\" class=\"resizable\" src=\"https:\/\/www.myopenmath.com\/multiembedq.php?id=17465&amp;theme=oea&amp;iframe_resize_id=mom3\" width=\"100%\" height=\"350\"><\/iframe>\r\n\r\n<\/div>\r\n<h2>Taxes\r\n<a href=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1141\/2017\/03\/27192407\/5120304358_f64b93a2ec_o.jpg\"><img class=\" wp-image-2212 aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1141\/2017\/03\/27192407\/5120304358_f64b93a2ec_o-300x212.jpg\" alt=\"magnifying lens over the word &quot;tax&quot;\" width=\"442\" height=\"312\" \/><\/a><\/h2>\r\nGovernments collect taxes to pay for the services they provide. In the United States, federal income taxes help fund the military, the environmental protection agency, and thousands of other programs. Property taxes help fund schools. Gasoline taxes help pay for road improvements. While very few people enjoy paying taxes, they are necessary to pay for the services we all depend upon.\r\n\r\nTaxes can be computed in a variety of ways, but are typically computed as a percentage of a sale, of one\u2019s income, or of one\u2019s assets.\r\n<div class=\"textbox exercises\">\r\n<h3>Example: Sales Tax<\/h3>\r\nThe sales tax rate in a city is 9.3%. How much sales tax will you pay on a $140 purchase?\r\n[reveal-answer q=\"620729\"]Show Solution[\/reveal-answer]\r\n[hidden-answer a=\"620729\"]\r\n\r\nThe sales tax will be 9.3% of $140. To compute this, we multiply $140 by the percent written as a decimal: $140(0.093) = $13.02.\r\n\r\n[\/hidden-answer]\r\n<iframe id=\"mom1\" class=\"resizable\" src=\"https:\/\/www.myopenmath.com\/multiembedq.php?id=80109&amp;theme=oea&amp;iframe_resize_id=mom1\" width=\"100%\" height=\"200\"><\/iframe>\r\n\r\n<\/div>\r\n&nbsp;\r\n\r\nWhen taxes are not given as a fixed percentage rate, sometimes it is necessary to calculate the <strong>effective tax rate<\/strong>:<strong>\u00a0<\/strong>the equivalent percent rate of the tax paid out of the dollar amount the tax is based on.\r\n<div class=\"textbox exercises\">\r\n<h3>Example: Property Tax<\/h3>\r\nJaquim\u00a0paid $3,200 in property taxes on his\u00a0house valued at $215,000 last year. What is the effective tax rate?\r\n[reveal-answer q=\"696377\"]Show Solution[\/reveal-answer]\r\n[hidden-answer a=\"696377\"]We can compute the equivalent percentage: 3200\/215000 = 0.01488, or about 1.49% effective rate.[\/hidden-answer]\r\n\r\n<\/div>\r\nTaxes are often referred to as progressive, regressive, or flat.\r\n<ul>\r\n \t<li>A <strong>flat tax<\/strong>, or proportional tax, charges a constant percentage rate.<\/li>\r\n \t<li>A <strong>progressive tax<\/strong> increases the percent rate as the base amount increases.<\/li>\r\n \t<li>A <strong>regressive tax <\/strong>decreases the percent rate as the base amount increases.<\/li>\r\n<\/ul>\r\n<div class=\"textbox exercises\">\r\n<h3>Example: Federal Income Tax<\/h3>\r\nThe United States federal income tax on earned wages is an example of a progressive tax. People with a higher wage income pay a higher percent tax on their income.\r\n\r\nFor a single person in 2011, adjusted gross income (income after deductions) under $8,500 was taxed at 10%. Income over $8,500 but under $34,500 was taxed at 15%.\r\n<h4>Earning $10,000<\/h4>\r\nStephen earned\u00a0$10,000 in 2011. He would pay 10% on the portion of his\u00a0income under $8,500, and 15% on the income over $8,500.\r\n\r\n8500(0.10) = 850 \u00a0 \u00a0 10% of $8500\r\n1500(0.15) = 225 \u00a0 \u00a0 \u00a015% of the remaining $1500 of income\r\nTotal tax:\u00a0\u00a0 = $1075\r\n\r\nWhat was Stephen's effective tax rate?\r\n[reveal-answer q=\"696772\"]Show Solution[\/reveal-answer]\r\n[hidden-answer a=\"696772\"]The effective tax rate paid is 1075\/10000 = 10.75%[\/hidden-answer]\r\n\r\n&nbsp;\r\n<h4>Earning $30,000<\/h4>\r\nD'Andrea\u00a0earned $30,000 in 2011. She would also pay 10% on the portion of her\u00a0income under $8,500, and 15% on the income over $8,500.\r\n\r\n8500(0.10) = 850\u00a0\u00a0\u00a0\u00a0\u00a0 10% of $8500\r\n21500(0.15) = 3225\u00a0\u00a0\u00a0 15% of the remaining $21500 of income\r\nTotal tax:\u00a0\u00a0 = $4075\r\n\r\nWhat was D'Andrea's effective tax rate?\r\n[reveal-answer q=\"648795\"]Show Solution[\/reveal-answer]\r\n[hidden-answer a=\"648795\"]The effective tax rate paid is 4075\/30000 = 13.58%.[\/hidden-answer]\r\n\r\n&nbsp;\r\n\r\nNotice that the effective rate has increased with income, showing this is a progressive tax.\r\n\r\n<\/div>\r\n&nbsp;\r\n<div class=\"textbox exercises\">\r\n<h3>Example: Gasoline Tax<\/h3>\r\nA gasoline tax is a flat tax when considered in terms of consumption. A tax of, say, $0.30 per gallon is proportional to the amount of gasoline purchased. Someone buying 10 gallons of gas at $4 a gallon would pay $3 in tax, which is $3\/$40 = 7.5%. Someone buying 30 gallons of gas at $4 a gallon would pay $9 in tax, which is $9\/$120 = 7.5%, the same effective rate.\r\n\r\nHowever, in terms of income, a gasoline tax is often considered a regressive tax. It is likely that someone earning $30,000 a year and someone earning $60,000 a year will drive about the same amount. If both pay $60 in gasoline taxes over a year, the person earning $30,000 has paid 0.2% of their income, while the person earning $60,000 has paid 0.1% of their income in gas taxes.\r\n\r\n<\/div>\r\n&nbsp;\r\n<div class=\"textbox key-takeaways\">\r\n<h3>Try It<\/h3>\r\nA sales tax is a fixed percentage tax on a person\u2019s purchases. Is this a flat, progressive, or regressive tax?\r\n\r\n[practice-area rows=\"4\"][\/practice-area]\r\n[reveal-answer q=\"807267\"]Show Solution[\/reveal-answer]\r\n[hidden-answer a=\"807267\"]While sales tax is a flat percentage rate, it is often considered a regressive tax for the same reasons as the gasoline tax.[\/hidden-answer]\r\n\r\n<iframe id=\"mom5\" class=\"resizable\" src=\"https:\/\/www.myopenmath.com\/multiembedq.php?id=65941&amp;theme=oea&amp;iframe_resize_id=mom5\" width=\"100%\" height=\"650\"><\/iframe>\r\n\r\n<\/div>","rendered":"<div class=\"textbox learning-objectives\">\n<h3>Learning Outcomes<\/h3>\n<ul>\n<li>Identify and apply a solution\u00a0pathway for multi-step problems<\/li>\n<\/ul>\n<\/div>\n<p>In this section we will bring together the mathematical tools we\u2019ve reviewed, and use them to approach more complex problems. In many problems, it is tempting to take the given information, plug it into whatever formulas you have handy, and hope that the result is what you were supposed to find. Chances are, this approach has served you well in other math classes.<\/p>\n<p>This approach does not work well with real life problems, however. Read on to learn how to use a generalized problem solving approach to solve a wide variety of quantitative problems, including how taxes are calculated.<\/p>\n<h2>Problem Solving and Estimating<\/h2>\n<p>Problem solving is best approached by first starting at the end: identifying exactly what you are looking for. From there, you then work backwards, asking \u201cwhat information and procedures will I need to find this?\u201d Very few interesting questions can be answered in one mathematical step; often times you will need to chain together a <strong>solution pathway<\/strong>, a series of steps that will allow you to answer the question.<\/p>\n<div class=\"textbox\">\n<h3>Problem Solving Process<\/h3>\n<ol>\n<li>Identify the question you\u2019re trying to answer.<\/li>\n<li>Work backwards, identifying the information you will need and the relationships you will use to answer that question.<\/li>\n<li>Continue working backwards, creating a solution pathway.<\/li>\n<li>If you are missing necessary information, look it up or estimate it. If you have unnecessary information, ignore it.<\/li>\n<li>Solve the problem, following your solution pathway.<\/li>\n<\/ol>\n<\/div>\n<p>In most problems we work, we will be approximating a solution, because we will not have perfect information. We will begin with a few examples where we will be able to approximate the solution using basic knowledge from our lives.<\/p>\n<p>In the first example, we will need to think about time scales, we are asked to find how many times a heart beats in a year, but usually we measure heart rate in beats per minute.<\/p>\n<div class=\"textbox exercises\">\n<h3>Examples<\/h3>\n<p>How many times does your heart beat in a year?<\/p>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q630883\">Show Solution<\/span><\/p>\n<div id=\"q630883\" class=\"hidden-answer\" style=\"display: none\">\n<p>This question is asking for the rate of heart beats per year. Since a year is a long time to measure heart beats for, if we knew the rate of heart beats per minute, we could scale that quantity up to a year. So the information we need to answer this question is heart beats per minute. This is something you can easily measure by counting your pulse while watching a clock for a minute.<\/p>\n<p>Suppose you count 80 beats in a minute. To convert this to beats per year:<\/p>\n<p>[latex]\\displaystyle\\frac{80\\text{ beats}}{1\\text{ minute}}\\cdot\\frac{60\\text{ minutes}}{1\\text{ hour}}\\cdot\\frac{24\\text{ hours}}{1\\text{ day}}\\cdot\\frac{365\\text{ days}}{1\\text{ year}}=42,048,000\\text{ beats per year}[\/latex]<\/p>\n<\/div>\n<\/div>\n<\/div>\n<p>The technique that helped us solve the last problem was to get the number of heartbeats in a minute translated into the number of heartbeats in a year. Converting units from one to another, like minutes to years is a common tool for solving problems.<\/p>\n<p>In the next example, we show how to infer the thickness of something too small to measure with every-day tools. Before precision instruments were widely available, scientists and engineers had to get creative with ways to measure either very small or very large things. Imagine how early astronomers inferred the distance to stars, or the circumference of the earth.<\/p>\n<div class=\"textbox exercises\">\n<h3>Example<\/h3>\n<p>How thick is a single sheet of paper? How much does it weigh?<\/p>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q688739\">Show Solution<\/span><\/p>\n<div id=\"q688739\" class=\"hidden-answer\" style=\"display: none\">\n<p>While you might have a sheet of paper handy, trying to measure it would be tricky. Instead we might imagine a stack of paper, and then scale the thickness and weight to a single sheet. If you\u2019ve ever bought paper for a printer or copier, you probably bought a ream, which contains 500 sheets. We could estimate that a ream of paper is about 2 inches thick and weighs about 5 pounds. Scaling these down,<\/p>\n<p>[latex]\\displaystyle\\frac{2\\text{ inches}}{\\text{ream}}\\cdot\\frac{1\\text{ ream}}{500\\text{ pages}}=0.004\\text{ inches per sheet}[\/latex]<\/p>\n<p>[latex]\\displaystyle\\frac{5\\text{ pounds}}{\\text{ream}}\\cdot\\frac{1\\text{ ream}}{500\\text{ pages}}=0.01\\text{ pounds per sheet, or }=0.16\\text{ ounces per sheet.}[\/latex]<\/p>\n<\/div>\n<\/div>\n<p>The first two example questions in this set are examined in more detail here.<\/p>\n<p><iframe loading=\"lazy\" id=\"oembed-1\" title=\"Estimating with imperfect information\" width=\"500\" height=\"281\" src=\"https:\/\/www.youtube.com\/embed\/xF5BNEr0gjo?feature=oembed&#38;rel=0\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n<\/div>\n<p>We can infer a measurement by using scaling. \u00a0If 500 sheets of paper is two inches thick, then we could use proportional reasoning to infer the thickness of one sheet of paper.<\/p>\n<p>&nbsp;<\/p>\n<p>In the next example, we use proportional reasoning to determine how many calories are in a mini muffin when you are given the amount of calories for a regular sized muffin.<\/p>\n<div class=\"textbox exercises\">\n<h3>Example<\/h3>\n<p>A recipe for zucchini muffins states that it yields 12 muffins, with 250 calories per muffin. You instead decide to make mini-muffins, and the recipe yields 20 muffins. If you eat 4, how many calories will you consume?<\/p>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q397938\">Show Solution<\/span><\/p>\n<div id=\"q397938\" class=\"hidden-answer\" style=\"display: none\">\n<p>There are several possible solution pathways to answer this question. We will explore one.<\/p>\n<p>To answer the question of how many calories 4 mini-muffins will contain, we would want to know the number of calories in each mini-muffin. To find the calories in each mini-muffin, we could first find the total calories for the entire recipe, then divide it by the number of mini-muffins produced. To find the total calories for the recipe, we could multiply the calories per standard muffin by the number per muffin. Notice that this produces a multi-step solution pathway. It is often easier to solve a problem in small steps, rather than trying to find a way to jump directly from the given information to the solution.<\/p>\n<p>We can now execute our plan:<\/p>\n<p>[latex]\\displaystyle{12}\\text{ muffins}\\cdot\\frac{250\\text{ calories}}{\\text{muffin}}=3000\\text{ calories for the whole recipe}[\/latex]<\/p>\n<p>[latex]\\displaystyle\\frac{3000\\text{ calories}}{20\\text{ mini-muffins}}=\\text{ gives }150\\text{ calories per mini-muffin}[\/latex]<\/p>\n<p>[latex]\\displaystyle4\\text{ mini-muffins}\\cdot\\frac{150\\text{ calories}}{\\text{mini-muffin}}=\\text{totals }600\\text{ calories consumed.}[\/latex]<\/p>\n<\/div>\n<\/div>\n<p>View the following video for more about the zucchini muffin problem.<\/p>\n<p><iframe loading=\"lazy\" id=\"oembed-2\" title=\"Multistep proportions \/ problem solving process\" width=\"500\" height=\"281\" src=\"https:\/\/www.youtube.com\/embed\/NVCwFO-w2z4?feature=oembed&#38;rel=0\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n<\/div>\n<p>We have found that ratios are very helpful when we know some information but it is not in the right units, or parts to answer our question. Making comparisons mathematically often involves using ratios and proportions. For the last<\/p>\n<div class=\"textbox exercises\">\n<h3>Example<\/h3>\n<p>You need to replace the boards on your deck. About how much will the materials cost?<\/p>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q36890\">Show Solution<\/span><\/p>\n<div id=\"q36890\" class=\"hidden-answer\" style=\"display: none\">\n<p>There are two approaches we could take to this problem: 1) estimate the number of boards we will need and find the cost per board, or 2) estimate the area of the deck and find the approximate cost per square foot for deck boards. We will take the latter approach.<\/p>\n<p>For this solution pathway, we will be able to answer the question if we know the cost per square foot for decking boards and the square footage of the deck. To find the cost per square foot for decking boards, we could compute the area of a single board, and divide it into the cost for that board. We can compute the square footage of the deck using geometric formulas. So first we need information: the dimensions of the deck, and the cost and dimensions of a single deck board.<\/p>\n<p>Suppose that measuring the deck, it is rectangular, measuring 16 ft by 24 ft, for a total area of 384 ft<sup>2<\/sup>.<\/p>\n<p>From a visit to the local home store, you find that an 8 foot by 4 inch cedar deck board costs about $7.50. The area of this board, doing the necessary conversion from inches to feet, is:<\/p>\n<p>[latex]\\displaystyle{8}\\text{ feet}\\cdot4\\text{ inches}\\cdot\\frac{1\\text{ foot}}{12\\text{ inches}}=2.667\\text{ft}^2{.}[\/latex] The cost per square foot is then\u00a0[latex]\\displaystyle\\frac{\\$7.50}{2.667\\text{ft}^2}=\\$2.8125\\text{ per ft}^2{.}[\/latex]<\/p>\n<p>This will allow us to estimate the material cost for the whole 384 ft<sup>2<\/sup> deck<\/p>\n<p>[latex]\\displaystyle\\$384\\text{ft}^2\\cdot\\frac{\\$2.8125}{\\text{ft}^2}=\\$1080\\text{ total cost.}[\/latex]<\/p>\n<p>Of course, this cost estimate assumes that there is no waste, which is rarely the case. It is common to add at least 10% to the cost estimate to account for waste.<\/p>\n<\/div>\n<\/div>\n<p>This example is worked through in the following video.<\/p>\n<p><iframe loading=\"lazy\" id=\"oembed-3\" title=\"Estimating the cost of a deck\" width=\"500\" height=\"281\" src=\"https:\/\/www.youtube.com\/embed\/adPGfeTy-Pc?feature=oembed&#38;rel=0\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n<\/div>\n<p>&nbsp;<\/p>\n<div class=\"textbox exercises\">\n<h3>Example<\/h3>\n<p>Is it worth buying a Hyundai Sonata hybrid instead the regular Hyundai Sonata?<\/p>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q499109\">Show Solution<\/span><\/p>\n<div id=\"q499109\" class=\"hidden-answer\" style=\"display: none\">\n<p>To make this decision, we must first decide what our basis for comparison will be. For the purposes of this example, we\u2019ll focus on fuel and purchase costs, but environmental impacts and maintenance costs are other factors a buyer might consider.<\/p>\n<p>It might be interesting to compare the cost of gas to run both cars for a year. To determine this, we will need to know the miles per gallon both cars get, as well as the number of miles we expect to drive in a year. From that information, we can find the number of gallons required from a year. Using the price of gas per gallon, we can find the running cost.<\/p>\n<p>From Hyundai\u2019s website, the 2013 Sonata will get 24 miles per gallon (mpg) in the city, and 35 mpg on the highway. The hybrid will get 35 mpg in the city, and 40 mpg on the highway.<\/p>\n<p>An average driver drives about 12,000 miles a year. Suppose that you expect to drive about 75% of that in the city, so 9,000 city miles a year, and 3,000 highway miles a year.<\/p>\n<p>We can then find the number of gallons each car would require for the year.<\/p>\n<p><strong>Sonata:<\/strong> [latex]\\displaystyle{9000}\\text{ city miles}\\cdot\\frac{1\\text{ gallon}}{24\\text{ city miles}}+3000\\text{ highway miles}\\cdot\\frac{1\\text{ gallon}}{35\\text{ highway miles}}=460.7\\text{ gallons}[\/latex]<\/p>\n<p><strong>Hybrid:<\/strong>\u00a0[latex]\\displaystyle{9000}\\text{ city miles}\\cdot\\frac{1\\text{ gallon}}{35\\text{ city miles}}+3000\\text{ highway miles}\\cdot\\frac{1\\text{ gallon}}{40\\text{ highway miles}}=332.1\\text{ gallons}[\/latex]<\/p>\n<p>If gas in your area averages about $3.50 per gallon, we can use that to find the running cost:<\/p>\n<p><strong>Sonata:<\/strong>\u00a0[latex]\\displaystyle{460.7}\\text{ gallons}\\cdot\\frac{\\$3.50}{\\text{gallon}}=\\$1612.45[\/latex]<\/p>\n<p><strong>Hybrid:<\/strong> [latex]\\displaystyle{332.1}\\text{ gallons}\\cdot\\frac{\\$3.50}{\\text{gallon}}=\\$1162.35[\/latex]<\/p>\n<p>The hybrid will save $450.10 a year. The gas costs for the hybrid are about [latex]\\displaystyle\\frac{\\$450.10}{\\$1612.45}[\/latex] = 0.279 = 27.9% lower than the costs for the standard Sonata.<\/p>\n<p>While both the absolute and relative comparisons are useful here, they still make it hard to answer the original question, since \u201cis it worth it\u201d implies there is some tradeoff for the gas savings. Indeed, the hybrid Sonata costs about $25,850, compared to the base model for the regular Sonata, at $20,895.<\/p>\n<p>To better answer the \u201cis it worth it\u201d question, we might explore how long it will take the gas savings to make up for the additional initial cost. The hybrid costs $4965 more. With gas savings of $451.10 a year, it will take about 11 years for the gas savings to make up for the higher initial costs.<\/p>\n<p>We can conclude that if you expect to own the car 11 years, the hybrid is indeed worth it. If you plan to own the car for less than 11 years, it may still be worth it, since the resale value of the hybrid may be higher, or for other non-monetary reasons. This is a case where math can help guide your decision, but it can\u2019t make it for you.<\/p>\n<\/div>\n<\/div>\n<p>This question pulls together all the skills discussed previously on this page, as the video demonstration illustrates.<\/p>\n<p><iframe loading=\"lazy\" id=\"oembed-4\" title=\"Guiding decision using math: Sonata vs Hybrid\" width=\"500\" height=\"281\" src=\"https:\/\/www.youtube.com\/embed\/HXmc-EkOYJE?feature=oembed&#38;rel=0\" frameborder=\"0\" allowfullscreen=\"allowfullscreen\"><\/iframe><\/p>\n<\/div>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<div class=\"textbox key-takeaways\">\n<h3>Try It<\/h3>\n<p><iframe loading=\"lazy\" id=\"mom1\" class=\"resizable\" src=\"https:\/\/www.myopenmath.com\/multiembedq.php?id=17454&amp;theme=oea&amp;iframe_resize_id=mom1\" width=\"100%\" height=\"350\"><\/iframe><\/p>\n<hr \/>\n<p><iframe loading=\"lazy\" id=\"mom2\" class=\"resizable\" src=\"https:\/\/www.myopenmath.com\/multiembedq.php?id=17457&amp;theme=oea&amp;iframe_resize_id=mom2\" width=\"100%\" height=\"350\"><\/iframe><\/p>\n<hr \/>\n<p><iframe loading=\"lazy\" id=\"mom3\" class=\"resizable\" src=\"https:\/\/www.myopenmath.com\/multiembedq.php?id=17465&amp;theme=oea&amp;iframe_resize_id=mom3\" width=\"100%\" height=\"350\"><\/iframe><\/p>\n<\/div>\n<h2>Taxes<br \/>\n<a href=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1141\/2017\/03\/27192407\/5120304358_f64b93a2ec_o.jpg\"><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-2212 aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/1141\/2017\/03\/27192407\/5120304358_f64b93a2ec_o-300x212.jpg\" alt=\"magnifying lens over the word &quot;tax&quot;\" width=\"442\" height=\"312\" \/><\/a><\/h2>\n<p>Governments collect taxes to pay for the services they provide. In the United States, federal income taxes help fund the military, the environmental protection agency, and thousands of other programs. Property taxes help fund schools. Gasoline taxes help pay for road improvements. While very few people enjoy paying taxes, they are necessary to pay for the services we all depend upon.<\/p>\n<p>Taxes can be computed in a variety of ways, but are typically computed as a percentage of a sale, of one\u2019s income, or of one\u2019s assets.<\/p>\n<div class=\"textbox exercises\">\n<h3>Example: Sales Tax<\/h3>\n<p>The sales tax rate in a city is 9.3%. How much sales tax will you pay on a $140 purchase?<\/p>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q620729\">Show Solution<\/span><\/p>\n<div id=\"q620729\" class=\"hidden-answer\" style=\"display: none\">\n<p>The sales tax will be 9.3% of $140. To compute this, we multiply $140 by the percent written as a decimal: $140(0.093) = $13.02.<\/p>\n<\/div>\n<\/div>\n<p><iframe loading=\"lazy\" id=\"mom1\" class=\"resizable\" src=\"https:\/\/www.myopenmath.com\/multiembedq.php?id=80109&amp;theme=oea&amp;iframe_resize_id=mom1\" width=\"100%\" height=\"200\"><\/iframe><\/p>\n<\/div>\n<p>&nbsp;<\/p>\n<p>When taxes are not given as a fixed percentage rate, sometimes it is necessary to calculate the <strong>effective tax rate<\/strong>:<strong>\u00a0<\/strong>the equivalent percent rate of the tax paid out of the dollar amount the tax is based on.<\/p>\n<div class=\"textbox exercises\">\n<h3>Example: Property Tax<\/h3>\n<p>Jaquim\u00a0paid $3,200 in property taxes on his\u00a0house valued at $215,000 last year. What is the effective tax rate?<\/p>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q696377\">Show Solution<\/span><\/p>\n<div id=\"q696377\" class=\"hidden-answer\" style=\"display: none\">We can compute the equivalent percentage: 3200\/215000 = 0.01488, or about 1.49% effective rate.<\/div>\n<\/div>\n<\/div>\n<p>Taxes are often referred to as progressive, regressive, or flat.<\/p>\n<ul>\n<li>A <strong>flat tax<\/strong>, or proportional tax, charges a constant percentage rate.<\/li>\n<li>A <strong>progressive tax<\/strong> increases the percent rate as the base amount increases.<\/li>\n<li>A <strong>regressive tax <\/strong>decreases the percent rate as the base amount increases.<\/li>\n<\/ul>\n<div class=\"textbox exercises\">\n<h3>Example: Federal Income Tax<\/h3>\n<p>The United States federal income tax on earned wages is an example of a progressive tax. People with a higher wage income pay a higher percent tax on their income.<\/p>\n<p>For a single person in 2011, adjusted gross income (income after deductions) under $8,500 was taxed at 10%. Income over $8,500 but under $34,500 was taxed at 15%.<\/p>\n<h4>Earning $10,000<\/h4>\n<p>Stephen earned\u00a0$10,000 in 2011. He would pay 10% on the portion of his\u00a0income under $8,500, and 15% on the income over $8,500.<\/p>\n<p>8500(0.10) = 850 \u00a0 \u00a0 10% of $8500<br \/>\n1500(0.15) = 225 \u00a0 \u00a0 \u00a015% of the remaining $1500 of income<br \/>\nTotal tax:\u00a0\u00a0 = $1075<\/p>\n<p>What was Stephen&#8217;s effective tax rate?<\/p>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q696772\">Show Solution<\/span><\/p>\n<div id=\"q696772\" class=\"hidden-answer\" style=\"display: none\">The effective tax rate paid is 1075\/10000 = 10.75%<\/div>\n<\/div>\n<p>&nbsp;<\/p>\n<h4>Earning $30,000<\/h4>\n<p>D&#8217;Andrea\u00a0earned $30,000 in 2011. She would also pay 10% on the portion of her\u00a0income under $8,500, and 15% on the income over $8,500.<\/p>\n<p>8500(0.10) = 850\u00a0\u00a0\u00a0\u00a0\u00a0 10% of $8500<br \/>\n21500(0.15) = 3225\u00a0\u00a0\u00a0 15% of the remaining $21500 of income<br \/>\nTotal tax:\u00a0\u00a0 = $4075<\/p>\n<p>What was D&#8217;Andrea&#8217;s effective tax rate?<\/p>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q648795\">Show Solution<\/span><\/p>\n<div id=\"q648795\" class=\"hidden-answer\" style=\"display: none\">The effective tax rate paid is 4075\/30000 = 13.58%.<\/div>\n<\/div>\n<p>&nbsp;<\/p>\n<p>Notice that the effective rate has increased with income, showing this is a progressive tax.<\/p>\n<\/div>\n<p>&nbsp;<\/p>\n<div class=\"textbox exercises\">\n<h3>Example: Gasoline Tax<\/h3>\n<p>A gasoline tax is a flat tax when considered in terms of consumption. A tax of, say, $0.30 per gallon is proportional to the amount of gasoline purchased. Someone buying 10 gallons of gas at $4 a gallon would pay $3 in tax, which is $3\/$40 = 7.5%. Someone buying 30 gallons of gas at $4 a gallon would pay $9 in tax, which is $9\/$120 = 7.5%, the same effective rate.<\/p>\n<p>However, in terms of income, a gasoline tax is often considered a regressive tax. It is likely that someone earning $30,000 a year and someone earning $60,000 a year will drive about the same amount. If both pay $60 in gasoline taxes over a year, the person earning $30,000 has paid 0.2% of their income, while the person earning $60,000 has paid 0.1% of their income in gas taxes.<\/p>\n<\/div>\n<p>&nbsp;<\/p>\n<div class=\"textbox key-takeaways\">\n<h3>Try It<\/h3>\n<p>A sales tax is a fixed percentage tax on a person\u2019s purchases. Is this a flat, progressive, or regressive tax?<\/p>\n<p><textarea aria-label=\"Your Answer\" rows=\"4\"><\/textarea><\/p>\n<div class=\"qa-wrapper\" style=\"display: block\"><span class=\"show-answer collapsed\" style=\"cursor: pointer\" data-target=\"q807267\">Show Solution<\/span><\/p>\n<div id=\"q807267\" class=\"hidden-answer\" style=\"display: none\">While sales tax is a flat percentage rate, it is often considered a regressive tax for the same reasons as the gasoline tax.<\/div>\n<\/div>\n<p><iframe loading=\"lazy\" id=\"mom5\" class=\"resizable\" src=\"https:\/\/www.myopenmath.com\/multiembedq.php?id=65941&amp;theme=oea&amp;iframe_resize_id=mom5\" width=\"100%\" height=\"650\"><\/iframe><\/p>\n<\/div>\n\n\t\t\t <section class=\"citations-section\" role=\"contentinfo\">\n\t\t\t <h3>Candela Citations<\/h3>\n\t\t\t\t\t <div>\n\t\t\t\t\t\t <div id=\"citation-list-1049\">\n\t\t\t\t\t\t\t <div class=\"licensing\"><div class=\"license-attribution-dropdown-subheading\">CC licensed content, Original<\/div><ul class=\"citation-list\"><li>Learning objectives. <strong>Authored by<\/strong>: Lumen Learning. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY: Attribution<\/a><\/em><\/li><\/ul><div class=\"license-attribution-dropdown-subheading\">CC licensed content, Shared previously<\/div><ul class=\"citation-list\"><li>Math in Society. <strong>Authored by<\/strong>: David Lippman. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"http:\/\/www.opentextbookstore.com\/mathinsociety\/\">http:\/\/www.opentextbookstore.com\/mathinsociety\/<\/a>. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by-sa\/4.0\/\">CC BY-SA: Attribution-ShareAlike<\/a><\/em><\/li><li>Estimating with imperfect information. <strong>Authored by<\/strong>: OCLPhase2&#039;s channel. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"https:\/\/youtu.be\/xF5BNEr0gjo\">https:\/\/youtu.be\/xF5BNEr0gjo<\/a>. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY: Attribution<\/a><\/em><\/li><li>Multistep proportions \/ problem solving process. <strong>Authored by<\/strong>: OCLPhase2&#039;s channel. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"https:\/\/youtu.be\/NVCwFO-w2z4\">https:\/\/youtu.be\/NVCwFO-w2z4<\/a>. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY: Attribution<\/a><\/em><\/li><li>Estimating the cost of a deck. <strong>Authored by<\/strong>: OCLPhase2&#039;s channel. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"https:\/\/youtu.be\/adPGfeTy-Pc\">https:\/\/youtu.be\/adPGfeTy-Pc<\/a>. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY: Attribution<\/a><\/em><\/li><li>Guiding decision using math: Sonata vs Hybrid. <strong>Authored by<\/strong>: OCLPhase2&#039;s channel. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"https:\/\/youtu.be\/HXmc-EkOYJE\">https:\/\/youtu.be\/HXmc-EkOYJE<\/a>. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY: Attribution<\/a><\/em><\/li><li><strong>Authored by<\/strong>: Calita Kabir. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"https:\/\/flic.kr\/p\/8NsU6C\">https:\/\/flic.kr\/p\/8NsU6C<\/a>. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY: Attribution<\/a><\/em><\/li><li>Question ID 65951. <strong>Authored by<\/strong>: Parker, Gary. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY: Attribution<\/a><\/em>. <strong>License Terms<\/strong>: IMathAS Community License CC-BY + GPL<\/li><li>Question ID 80109. <strong>Authored by<\/strong>: Lumen Learning. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY: Attribution<\/a><\/em>. <strong>License Terms<\/strong>: IMathAS Community License CC-BY + GPL<\/li><\/ul><\/div>\n\t\t\t\t\t\t <\/div>\n\t\t\t\t\t <\/div>\n\t\t\t <\/section>","protected":false},"author":21,"menu_order":3,"template":"","meta":{"_candela_citation":"[{\"type\":\"original\",\"description\":\"Learning objectives\",\"author\":\"Lumen Learning\",\"organization\":\"\",\"url\":\"\",\"project\":\"\",\"license\":\"cc-by\",\"license_terms\":\"\"},{\"type\":\"cc\",\"description\":\"Math in Society\",\"author\":\"David 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