Question

the half - life of a particular radioactive substance is 1 year. if you started with 40 grams of this substance, how much of it would remain after 3 years? remaining amount = 40(1 - ?)^ remaining amount = i(1 - r)^t enter the number that belongs in the green box

Explanation:

Step1: Identify decay rate

For a substance with half - life, the decay rate $r$ for each half - life period is $\frac{1}{2}$.

Step2: Determine exponent

The half - life is 1 year and the time $t = 3$ years. Since the half - life is 1 year, the number of half - life periods is 3.

Answer:

The number in the green box is $\frac{1}{2}$ and the exponent is 3.