Question

In a box containing 100 bulbs, 10 are defective. The probability that out of a sample of 5 bulbs, none is defective is

(A) 10⁻¹

(B)

(C)

(D)

Answer 1

The repeated selections of defective bulbs from a box are Bernoulli trials. Let X denote the number of defective bulbs out of a sample of 5 bulbs.

Probability of getting a defective bulb, p

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

P (none of the bulbs is defective) = P(X = 0)

The correct answer is C.