The hourly temperature at Portland, Oregon, on a particular day is recorded below. 1 A. M.

2

3

4

5

6

7

8

9

10

11

12 Noon

46°

44°

43°

41°

40°

40°

41°

43°

46°

52°

65°

69°

1 P. M.

2

3

4

5

6

7

8

9

10

11

12 Midnight

72°

74°

75°

75°

77°

75°

74°

70°

62°

55°

51°

48°

a. Find the amplitude of a sinusoidal function that models this temperature variation.

b. Find the vertical shift of a sinusoidal function that models this temperature variation.
c. What is the period of a sinusoidal function that models this temperature variation?
d. Use t = 0 at 5 P. M. to write a sinusoidal function that models this temp. variation.
e. What is the model’s temperature at 10 A. M.? Compare this to the actual value?