Question

The probability that a student is not a swimmer is. Then the probability that out of five students, four are swimmers is

(A) (B)

(C) (D) None of these

Answer 1

The repeated selection of students who are swimmers are Bernoulli trials. Let X denote the number of students, out of 5 students, who are swimmers.

Probability of students who are not swimmers, q

Clearly, X has a binomial distribution with n = 5 and

P (four students are swimmers) = P(X = 4)

Therefore, the correct answer is A.