Question

Radium 226, which had been used for cancer treatment, decays with half-life of 1622 years. Suppose there is 2.3gram sample of Raduim 226. How long will it take to have 1.7 grams remaining?

Answer 1

1/2=k^1622

k=(1/2)^(1/1622)

1.7=2.3(1/2)^(t/1622)

(1.7/2.3)=(1/2)^(t/1622)

ln(1.7/2.3)/ln(1/2)=t/1622

t=1622(ln(1.7/2.3))/ln(1/2)

t≈707.35