Set 1: Exponential Functions (Advanced)

**Choice B is the best answer.** After 3 half-lives: 320 / 2 to the power of 3 = 40 grams

Explanation

Answer: B

PROBLEM

A substance with half-life of 1 hour starts at 320 grams. How many grams remain after 3 hours?

A.

41

B.

40

✓ Correct

C.

20

D.

39

Detailed Explanation

Choice B is the best answer. After 3 half-lives: 320 / 2 to the power of 3 = 40 grams

Why others are wrong:

A: 41 is incorrect because it does not satisfy the equation.

C: 20 is incorrect because it does not satisfy the equation.

D: 39 is incorrect because it does not satisfy the equation.