Question

A box contains nine bulbs out of which 4 are defective. If four bulbs are chosen at random, find the probability that atleast one bulb is good.

Answer 1

Answer:

probability of at least one bulb is good=1- probability of no bulb is good(i.e. all bulbs are defective)..... so P(all bulbs are defective)=4c4=4!/4!=1 and total no of possible outcomes= 9c4=9!/4!5!=1/126 so,the required probability=1-1/126=125/126