Set 2: Exponential Functions (Advanced)

**Choice C is the best answer.** After 2 half-lives: 640 / 2 to the power of 2 = 160 grams

Explanation

Answer: C

PROBLEM

A substance with half-life of 1 hour starts at 640 grams. How many grams remain after 2 hours?

159

160

✓ Correct

161

Detailed Explanation

Choice C is the best answer. After 2 half-lives: 640 / 2 to the power of 2 = 160 grams

Why others are wrong:

A: 80 is incorrect because it does not satisfy the equation.

B: 159 is incorrect because it does not satisfy the equation.

D: 161 is incorrect because it does not satisfy the equation.