A muon formed high in the Earth's atmosphere travels at speed $v=0.990 c$ for a distance of $4.60 \mathrm{km}$ before it decays into an electron, a neutrino, and an anti neutrino $\left(\mu^{-} \rightarrow \mathrm{e}^{-}+\nu+\bar{\nu}\right) .$ (a) How long does the muon live, as
measured in its reference frame? (b) How far does the Earth travel, as measured in the frame of the muon?