Question

You have 32 grams of a radioactive kind of gold. If its half-life is 3 days, how much will be left after 6 days?

a. 5 grams
b. 4 grams
c. 16 grams
d. 8 grams

Answer 1

d. 8 grams.

Explanation:

After 1 half life there is 1/2 * 32 = 16 grams left , after another half-life ( at 6 days) there is 1/2 * 16 = 8 grams left.

Answer 2

d. 8 grams
The equation
Ending Amount = Beginning Amount / 2(time / half-life)
32/2^(6/3)
32/2^2
32/4
=8