Set 3: Exponential Functions (Advanced)

[Variation 1] **Choice D is the best answer.** After 3 half-lives: 320 / 2 to the power of 3 = 40 grams

Explanation

Answer: D

PROBLEM

Recent studies show that a substance with half-life of 1 hour starts at 320 grams. How many grams remain after 3 hours?

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

✓ Correct

Detailed Explanation

[Variation 1] Choice D 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.

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

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