Question

A sample of 400 grams of radioactive substance decays according to the function A(t) = 400e^-.046t, where t is the time in years. How much of the substance will be left in the sample after 20 years? Round your answer to the nearest whole gram.

Answer 1

Answer: There will be 0.04 grams will be left in the sample after 20 years.

Explanation:

Since we have given that

`A(t)=400e^(-0.46t)`

Here, Initial amount of radioactive substance = 400 grams

We need to find the amount of substance that will be left in the sample after 20 years.

So, t = 20 years

So, it becomes,

`A(t)=400e^(-0.46* 20)\\\\A(t)=400e^(-9.2)\\\\A(t)=0.04\ grams`

Hence, there will be 0.04 grams will be left in the sample after 20 years.