7

Set 1: Exponential Functions (Advanced)

Explanation

Answer: C

PROBLEM

A substance with half-life of 1 hour starts at 320 grams. How many grams remain after 2 hours?

A substance with half-life of 1 hour starts at 320 grams. How many grams remain after 2 hours?

A.

79

B.

81

C.

80

✓ Correct
D.

78

Detailed Explanation

Choice C is the best answer. After 2 half-lives: 320 / 2 to the power of 2 = 80 grams

Why others are wrong:
A: 79 is incorrect because it does not satisfy the equation.
B: 81 is incorrect because it does not satisfy the equation.
D: 78 is incorrect because it does not satisfy the equation.