Thread: please help

Originally Posted by wvlilgurl

A man has 2 boxes of mathces, each of which contain n matches at the start. He selects a box at random and uses one match from it each time he lights a pipe. What is the probability that when he selects the box at random, the box is empty and the other box has k matches in it. k=0,1,2,..,n?

I'd suggest that you first get a feel for the question by substituting a concrete value for n. Try doing it when:

(a) n = 2.
(b) n = 3.
(c) n= 4.

This should give you some insight for tackling the more general question.