Question

the half - life of a particular radioactive substance is 3 years. if you started with 60 grams of this substance, how much of it would remain after 6 years?
remaining amount = 60(1 - ?)
remaining amount = i(1 - r)^t
enter the number that belongs in the green box.

Explanation:

Step1: Determine decay factor

The half - life is 3 years. In each half - life, half of the substance decays, so the decay rate $r=\frac{1}{2}$.

Step2: Determine number of half - lives

The time elapsed is $t = 6$ years and the half - life is 3 years. The number of half - lives $n=\frac{6}{3}=2$.

Answer:

$\frac{1}{2}$