Question

A radioactive substance decays so that after t years, the amount remaining, expressed as a percent of the original amount, is A(t)=100(1.3)^-tDetermine the rate of decay after 10 years

Answer 1

We have to use the following formula

`\begin{gathered} A(t)=100(1.3)^{\text{ -}t} \\ A(100)=100(1.3)^{\text{ -10 }} \\ A(100)=(100)/((1.3)^(10))=(100)/(13.786)=7.254 \\ \\ \end{gathered}`

We had to use the formula given to you, so it will decay 7.254% per year.