Which of the following represents the probability of 3 successes in 5 trials?

For exactly 3 successes in 5 trials, choose which 3 of the 5 trials are successes: 5C3. The probability of those outcomes is P(S)^3P(F)^2, since the remaining 2 trials are failures. Thus the expression is 5C3 P(S)^3 P(F)^2, choice B.

AI-written and checked against the verified answer.