(Solution Download) The power supply for a pacemaker is a small amount

The power supply for a pacemaker is a small amount of radioactive 238Pu. This nuclide decays by a decay with a half-life of 86 yr. The pacemaker is typically replaced every 10.0 yr.
(a) By what percentage does the activity of the 238Pu source decrease in 10 yr?
(b) The energy of the ? particles emitted is 5.6 MeV. Assume an efficiency of 100%-all of the a-particle energy is used to run the pacemaker. If the pacemaker starts with 1.0 mg of 238Pu, what is the power output initially and after 10.0 yr?