Algebra homework

Question

Iodine -131 has a half life of about 8 days. This means that approximately every 8 days, half the mass of the iodine decays into another element. If a container held a mass of 64 milligrams of iodine -131, how much is left after 40 days?

Answer 1

This is a problem in exponential decay.

t = days

m(t) = (64 mg) (0.5)^t/8

Plug in t=40 to get m(40) and finish from here.