{"id":5371,"date":"2021-03-17T23:34:40","date_gmt":"2021-03-17T23:34:40","guid":{"rendered":"https:\/\/courses.lumenlearning.com\/nwfsc-mathforliberalartscorequisite\/chapter\/introduction-to-the-normal-distribution\/"},"modified":"2021-03-24T20:08:59","modified_gmt":"2021-03-24T20:08:59","slug":"introduction-to-the-normal-distribution","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/nwfsc-mathforliberalartscorequisite\/chapter\/introduction-to-the-normal-distribution\/","title":{"raw":"Introduction to the Normal Distribution","rendered":"Introduction to the Normal Distribution"},"content":{"raw":"<figure id=\"fs-idp3364000\" class=\"splash ui-has-child-figcaption\"><span id=\"fs-idp63701744\"><img class=\"aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/132\/2016\/04\/21214540\/CNX_Stats_C06_CON.jpg\" alt=\"This photo shows many different pairs of shoes in various colors. The shoes appear to be hanging from a wall by cords.\" width=\"500\" \/><\/span><figcaption>If you ask enough people about their shoe size, you will find that your graphed data (histogram) is shaped like a bell curve and can be described as normally distributed. (credit: \u00d6mer \u00dcnl\u03cb)<\/figcaption><\/figure>\r\n<p id=\"intro001\">The normal distribution is widely used and even more widely abused. Its graph is bell-shaped. You see the bell curve in almost all disciplines. Some of these include psychology, business, economics, the sciences, nursing, and, of course, mathematics. Some of your instructors may use the normal distribution to help determine your grade. Most IQ scores are normally distributed. Often real-estate prices fit a normal distribution. The normal distribution is extremely important, but it cannot be applied to everything in the real world.<\/p>\r\n<p id=\"element-299\">In this chapter, you will study the normal distribution, the standard normal distribution, and applications associated with them.<\/p>\r\nThe normal distribution has two parameters (two numerical descriptive measures), the mean (<em>\u03bc<\/em>) and the standard deviation (<em>\u03c3<\/em>). If <em>X<\/em> is a quantity to be measured that has a normal distribution with mean (<em>\u03bc<\/em>) and standard deviation (<em>\u03c3<\/em>), we designate this by writing\r\n<figure id=\"fs-idm13606720\"><span id=\"id42732641\"><img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/132\/2016\/04\/21214543\/fig-ch06_01_01N.jpg\" alt=\"This is a frequency curve for a normal distribution. It shows a single peak in the center with the curve tapering down to the horizontal axis on each side. The distribution is symmetrical; it represents the random variable X having a normal distribution with a mean, m, and standard deviation, s.\" width=\"450\" \/><\/span><\/figure>\r\n<p id=\"element-396\">The curve is symmetrical about a vertical line drawn through the mean, <em>\u03bc<\/em>. As the notation indicates, the normal distribution depends only on the mean and the standard deviation. A change in the standard deviation, <em>\u03c3<\/em>, causes a change in the shape of the curve; the curve becomes fatter or skinnier depending on <em>\u03c3<\/em>. A change in <em>\u03bc<\/em> causes the graph to shift to the left or right. This means there are an infinite number of normal probability distributions. One of special interest is called the <strong>standard normal distribution<\/strong>.<\/p>\r\n\r\n<div id=\"fs-idp30947824\" class=\"note statistics collab ui-has-child-title\"><header>\r\n<div class=\"title\"><\/div>\r\n<\/header><\/div>","rendered":"<figure id=\"fs-idp3364000\" class=\"splash ui-has-child-figcaption\"><span id=\"fs-idp63701744\"><img decoding=\"async\" class=\"aligncenter\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/132\/2016\/04\/21214540\/CNX_Stats_C06_CON.jpg\" alt=\"This photo shows many different pairs of shoes in various colors. The shoes appear to be hanging from a wall by cords.\" width=\"500\" \/><\/span><figcaption>If you ask enough people about their shoe size, you will find that your graphed data (histogram) is shaped like a bell curve and can be described as normally distributed. (credit: \u00d6mer \u00dcnl\u03cb)<\/figcaption><\/figure>\n<p id=\"intro001\">The normal distribution is widely used and even more widely abused. Its graph is bell-shaped. You see the bell curve in almost all disciplines. Some of these include psychology, business, economics, the sciences, nursing, and, of course, mathematics. Some of your instructors may use the normal distribution to help determine your grade. Most IQ scores are normally distributed. Often real-estate prices fit a normal distribution. The normal distribution is extremely important, but it cannot be applied to everything in the real world.<\/p>\n<p id=\"element-299\">In this chapter, you will study the normal distribution, the standard normal distribution, and applications associated with them.<\/p>\n<p>The normal distribution has two parameters (two numerical descriptive measures), the mean (<em>\u03bc<\/em>) and the standard deviation (<em>\u03c3<\/em>). If <em>X<\/em> is a quantity to be measured that has a normal distribution with mean (<em>\u03bc<\/em>) and standard deviation (<em>\u03c3<\/em>), we designate this by writing<\/p>\n<figure id=\"fs-idm13606720\"><span id=\"id42732641\"><img decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images\/wp-content\/uploads\/sites\/132\/2016\/04\/21214543\/fig-ch06_01_01N.jpg\" alt=\"This is a frequency curve for a normal distribution. It shows a single peak in the center with the curve tapering down to the horizontal axis on each side. The distribution is symmetrical; it represents the random variable X having a normal distribution with a mean, m, and standard deviation, s.\" width=\"450\" \/><\/span><\/figure>\n<p id=\"element-396\">The curve is symmetrical about a vertical line drawn through the mean, <em>\u03bc<\/em>. As the notation indicates, the normal distribution depends only on the mean and the standard deviation. A change in the standard deviation, <em>\u03c3<\/em>, causes a change in the shape of the curve; the curve becomes fatter or skinnier depending on <em>\u03c3<\/em>. A change in <em>\u03bc<\/em> causes the graph to shift to the left or right. This means there are an infinite number of normal probability distributions. One of special interest is called the <strong>standard normal distribution<\/strong>.<\/p>\n<div id=\"fs-idp30947824\" class=\"note statistics collab ui-has-child-title\">\n<header>\n<div class=\"title\"><\/div>\n<\/header>\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-5371\">\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>Why It Matters: Normal Distribution. <strong>Authored by<\/strong>: Paul Jones. <strong>Provided by<\/strong>: Columbia Basin College. <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>Introductory Statistics . <strong>Authored by<\/strong>: Barbara Illowski, Susan Dean. <strong>Provided by<\/strong>: Open Stax. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"http:\/\/cnx.org\/contents\/30189442-6998-4686-ac05-ed152b91b9de@17.44\">http:\/\/cnx.org\/contents\/30189442-6998-4686-ac05-ed152b91b9de@17.44<\/a>. <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>: Download for free at http:\/\/cnx.org\/contents\/30189442-6998-4686-ac05-ed152b91b9de@17.44<\/li><\/ul><div class=\"license-attribution-dropdown-subheading\">All rights reserved content<\/div><ul class=\"citation-list\"><li>ck12.org normal distribution problems: Qualitative sense of normal distributions | Khan Academy. <strong>Authored by<\/strong>: Khan Academy . <strong>Located at<\/strong>: <a target=\"_blank\" href=\"https:\/\/www.youtube.com\/watch?t=427&#038;v=79duxPXpyKQ\">https:\/\/www.youtube.com\/watch?t=427&#038;v=79duxPXpyKQ<\/a>. <strong>License<\/strong>: <em>All Rights Reserved<\/em>. <strong>License Terms<\/strong>: Standard YouTube License<\/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":167848,"menu_order":7,"template":"","meta":{"_candela_citation":"[{\"type\":\"original\",\"description\":\"Why It Matters: Normal Distribution\",\"author\":\"Paul Jones\",\"organization\":\"Columbia Basin College\",\"url\":\"\",\"project\":\"\",\"license\":\"cc-by\",\"license_terms\":\"\"},{\"type\":\"copyrighted_video\",\"description\":\"ck12.org normal distribution problems: Qualitative sense of normal distributions | Khan Academy\",\"author\":\"Khan Academy \",\"organization\":\"\",\"url\":\"https:\/\/www.youtube.com\/watch?t=427&v=79duxPXpyKQ\",\"project\":\"\",\"license\":\"arr\",\"license_terms\":\"Standard YouTube 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