The only conclusion I can draw is that 5,9 km is wrong. When you use the time passed on Earth (2,0113346 s * 10^-5) to calculate the distance travelled according to an observer on Earth you get 2,0113346 s * 10^-5 * 299,792*0,994 = 5,9936413 km instead of 5,9 km!! Using this 5,9936413 you find 0,655585 km as the Lorentz contracted distance. And this gives you the speed v = 0,655585 / 2,2 * 10^-6 = 297,993 km/s. This is 297,993/299792 =0,994C !

I checked the lifetime of a muon: 2.1969811 * 10^-6. This gives you 5,9854 km (see calculations above).

the distance travelled is 5.99km not 5.9 as marius said.

Exactly, thanks Liam. Replacing on the board 5.9km for 5,99Km, all the calculations became correct. A little mistake of the teacher

Muons are a fundamental sub-atomic particles of the universe, unable to be further divided. Muons belong to the lepton group because they are only affected by 3 out of 4 of the fundamental forces. Muons decay into an electron and two kinds of neutrinos. They only exist on the earth after cosmic rays collisions in the atmosphere- the real and true unfundable skyCERN! 🙂