An elementary particle called a muon has an average lifetime of $2\mathrm{.}0{10}^{-6}s.$ Muons are created about $6$ to $8$ km above the Earth during cosmic ray collisions in the atmosphere. Without relativity the expected distance for a muon to travel would only be $0\mathrm{.}60$ km $.$ However, these particles are detected on Earth! Use relativity to determine how far the muon could travel if its speed is $0\mathrm{.}988$ c $.($Hint: find lifetime of the muon first then use $d=vt$ to find distance travelled.$)(3$ marks$)$