A softball pitcher has a 0.42 probability of throwing a strike for each pitch. If the softball pitcher throws 20 pitches, what is the probability that exactly 7 of them are strikes?
With p = 0.42 and q = 1-0.42 = 0.58 the probability of exactly 7 strikes out of 20 pitches is p7*q13*number of ways of choosing 7 from 20
or 0.427*0.5813*C(20,7) ≈ 0.15