**Practice Exam 3--Answers**

You can find answers to odd-numbered problems from the text in the text. Here are the answers to all other problems.

3)

5) (a) (b) (c)

8) (a) Half-life is about 31 days. (b) After about 72 days there will be 10 grams left.

To solve this problem, you have to notice that the initial amount, . Next, you have to find k from the equation . You obtain k = 0.0223.

9) (a) 18,221 people (b) 17.32 years (c) After 22.9 years. In the end of 2012.

10) 161.73 feet. (The height is equal to 200tan(0.68).)

14) Since t is in the II quadrant, sin(t) is positive, cos(t) is negative. Solving

for cos(t), we obtain . Hence, , , .

15) Amplitude: (a) 3 (b) 2 (c) 1 Period: (a) (b) 1 (c)

16) (A) (B)