Question

Strontium 90 is a radioactive material that decays according to the function

A(t)=A0e−0.0244t, where A0 is the initial amount present and A is the amount present at time t​ (in years). Assume that a scientist has a sample of 400 grams of strontium 90.


a) what is the decay rate of strontium 90?
b) how much strontium 90 is left after 40 years
c) when will only 300 grams of strontium 90 be left?
d) what is the half life of strontium 90?

Answer 1

hey mate

the time required is 28.41 days

Answer 2

decay rate is 2.44% per year

after 40 years, 400*(e^-0.976)=150.73 gm

300=400(e^-0.0244t)

0.75=e^-0.0244t

ln both sides

-0.2877=-0.0244t

t=11.79 years

t (1/2) occurs when ln(0.5)=-0.0244t

t=28.41 years

Have a nice day!