The Half-Life of a Muon Is 2

Multiple Choice

The half-life of a muon is 2.2 μs. How fast is it moving relative to an observer who says its half-life is 4.4 μs?

A) 0.87 c
B) 0.75 c
C) 0.97 c
D) 0.72 c
E) 0.50 c