MathDB

A salmon in a mountain river must overpass two waterfalls. In every minute, the probability of the salmon to overpass the first waterfall is

p > 0

, and the probability to overpass the second waterfall is

q > 0

. These two events are assumed to be independent. Compute the probability that the salmon did not overpass the first waterfall in

n

minutes, assuming that it did not overpass both waterfalls in that time.

2