A box contains nine bulbs out of which 4 are defective. If four bulbs are chosen at random, find the probability that at least one bulb is good. Probability
Q1. A box contains nine bulbs out of which 4 are defective. If four bulbs are chosen at random, find the probability that at least one bulb is good. Probability
Answer: 125/126
Explanation: P(all 4 bulbs defective) = C(4,4)/C(9,4) = 1/126. P(at least one good) = 1 − 1/126 = 125/126.