Special relativity : Problem solving (length contraction and time dilation)

In this video I discuss how to solve a simple problem where a muon with some life-time is created in upper atmosphere in space and then it travels down towards earth vertically with a constant velocity. The question is what is the maximum separation possible between earth surface and the approaching muon so as it can be detected at earth before it decays. I try solving the question by analyzing it from both frames- muon frame and earth frame.