Radioactive half-life a breeder reactor converts stable

Question

Question: Radioactive half-life a breeder reactor converts stable uranium-238 into the isotope plutonium-239. The decay of this isotope is given by

A(t) = A₀e^-0.00002876t

where A(t) is the amount of the isotope at time t, in years, and A₀ is the original amount.

(a) If A₀ = 500 lb, how much will be left after a human lifetime (use t = 80 years)?

(b) Find the half-life of this isotope.