You can determine the median number of attempts k it will take by calculating n such that ∑p(1-p)^(n) = 1/2 from n=0 to k-1. This is a geometric series which is easily solved. For p = 5% you get about 13.5 or in other words, half will get it after 14 ore more attempts and half will get it in 13 or fewer attempts.