Question

If a radioactive material has a half-life of 15 y what fraction of the material will remain after 30 y

Answer 1

Answer

1/4

Explanation

half life = 15 years

decay period = 30 years

The number of half-lives = 30 ÷ 15

                                         = 2 half lives  

1   ⇒(after 1st half life) ⇒   1/2   ⇒ (after 2nd half life) ⇒   1/4

     

The fraction that remained is 1/4.