A box contains 10 bulbs , of which just three are defective . if 5 bulbs are drawn at random,find the probabiltiy that sample of 5 contains
(1) exactly one defective bulbs
(2) exactly two defective bulbs
(3) no defective bulbs
10 bulbs are in total, in which 3 bulbs are defective.
So drawing 5 bulbs at random is done in 10C5 ways
1) Exactly one bulb is defective
It is done in 3C1 * 7C4
So the probability will be ( 3C1 * 7C4)/10C5
2) Exactly two bulbs are defective
It is done in 3C2 * 7C3
So the probability will be ( 3C2 * 7C3)/10C5
3).No defective bulbs
It is done in 3C0 * 7C5
So the probability will be ( 3C0 * 7C5)/10C5
So drawing 5 bulbs at random is done in 10C5 ways
1) Exactly one bulb is defective
It is done in 3C1 * 7C4
So the probability will be ( 3C1 * 7C4)/10C5
2) Exactly two bulbs are defective
It is done in 3C2 * 7C3
So the probability will be ( 3C2 * 7C3)/10C5
3).No defective bulbs
It is done in 3C0 * 7C5
So the probability will be ( 3C0 * 7C5)/10C5