A 9-kg quantity of radioactive isotope decays to 8 kg after 17 years. If the mass of the isotope at time 𝑡 t is

Question

A 9-kg quantity of radioactive isotope decays to 8 kg after 17 years. If the mass of the isotope at time t is m(t)=Ae^−kt, find the decay constant of the isotope.

K= ???

(I keep getting 0.0069 but is wrong)

Answer 1

8 = 9e^17k

0.8889 = e^17k

ln 0.08889 = 17k

-0.11778 = 17k

-0.006928 = k