p = .4
q = 1 - p = .6
1 = (p + q)⁴= p⁴ + 4p³q + 6p²q² + 4pq³ + q⁴
The terms tell us the probability of various cases. We want the case of 3 out of four believe in reincarnation, that's the term
P(3 of 4 believe) = 4p³q = 4(.4)³(.6) = 0.1536
Answer: 0.154
