What fraction of sample is left after

A. 3half- live
B. 5half-live

A. After 3 half-lives, only 1/8th (or 0.125) of the original sample is left.

B. After 5 half-lives, only 1/32nd (or 0.03125) of the original sample is left.

To calculate the fraction of a sample that is left after a certain number of half-lives, you can use the equation:

Fraction remaining = (1/2)^(number of half-lives)

A. To find the fraction remaining after 3 half-lives, plug in 3 into the equation:

Fraction remaining = (1/2)^(3)
= 1/8

So, after 3 half-lives, 1/8th of the original sample is left.

B. To find the fraction remaining after 5 half-lives, plug in 5 into the equation:

Fraction remaining = (1/2)^(5)
= 1/32

So, after 5 half-lives, 1/32nd of the original sample is left.