Question

A carton of 24 bulbs contain 6 defective bulbs. One bulb is drawn at random. What is the probability that the bulb is not defective? If the bulb selected is defective and it is not replaced and a second bulb is selected at random from the rest, what is the probability that the second bulb is defective?

Answer 1

There are 6 defective bulbs out of 24 bulbs
Favourable number of elementary events = 24 – 6 = 18

∴ Probability that the bulb is not defective =18/24=3/4

When the selected bulb is defective and not replaced, then
Total bulbs = 23, defective bulbs = 5

∴ Probability that the second bulb is defective =5/23