The half-life of a muon at rest is 1.5 s. Muons that have been accelerated to a

The half-life of a muon at rest is 1.5 μs. Muons that have been accelerated to a very high speed and are then held in a circular storage ring have a half-life of 7.5 μs.
a. What is the speed, as a fraction of c, of the muons in the storage ring?
b. What is the total energy of a muon in the storage ring? The mass of a muon is 207 times the mass of an electron.