Solution to Odd-Numbered Exercises

1. Terry starts at an elevation of 3000 feet and descends 70 feet per second.

3. 3 miles per hour

5. $d\left(t\right)=100 - 10t$

7. $45 per training session.

9. The rate of change is 0.1. For every additional minute talked, the monthly charge increases by $0.1 or 10 cents. The initial value is 24. When there are no minutes talked, initially the charge is $24.

11. The slope is –400. This means for every year between 1960 and 1989, the population dropped by 400 per year in the city.

13. c

15. 2,300

17. 64,170

19. $P\left(t\right)=75,000+2500t$

21. (–30, 0) Thirty years before the start of this model, the town had no citizens. (0, 75,000) Initially, the town had a population of 75,000.

23. Ten years after the model began.

25. $W\left(t\right)=\text{7}.\text{5}t+0.\text{5}$

27. (–15, 0): The x-intercept is not a plausible set of data for this model because it means the baby weighed 0 pounds 15 months prior to birth. (0, 7.5): The baby weighed 7.5 pounds at birth.

29. At age 5.8 months.

31. $C\left(t\right)=12,025 - 205t$

33. (58.7, 0): In roughly 59 years, the number of people inflicted with the common cold would be 0. (0, 12,025): Initially there were 12,025 people afflicted by the common cold.

35. 2064

37. $y=-2t+180$

39. In 2070, the company’s profit will be zero.

41. $y=30t - 300$

43. (10, 0) In 1990, the profit earned zero profit.

45. Hawaii

47. During the year 1933

49. $105,620

51.

a. 696 people
b. 4 years
c. 174 people per year
d. 305 people
e. $P\left(t\right)=305+174t$
f. 2219 people

53.

a. $C\left(x\right)=0.15x+10$
b. The flat monthly fee is $10 and there is an additional $0.15 fee for each additional minute used
c. $113.05

55.

a. $P\left(t\right)=190t+4360$
b. 6640 moose

57.

a. $R\left(t\right)=16 - 2.1t$
b. 5.5 billion cubic feet
c. During the year 2017

59. More than 133 minutes

61. More than $42,857.14 worth of jewelry

63. $66,666.67