You have to get three heads and two tails, and there is more than one way of doing this. The formula isp(3) = 5C3 Ã— 0.5^3 Ã— 0.5^2where 5C3 = 5!/3!2! = 10 is the number of ways of selecting 3 things out of 5.This gives the probability of exactly three heads as 0.3125..
