Question

In a box containing 10 lamps, 4 of them are damaged. Two lamps are selected, at random, without replacement from the carton. What is the probability that both of the lamps selected are damaged?

		16/90
		16/100
		12/90
		12/100

Answer 1

In a box containing 10 lamps, 4 of them are damaged.

Two lamps are selected, at random, without replacement from the carton.

We have asked to find the probability that both lamps are damaged.

For first lamp there are 4 damaged lamp in the box. So probability is 4/10

We are not replacing the selected lamp, so now there are 3 damaged lamp in a box.

Hence P( second lamp is also damaged ) = 3/9

Therefore P ( both lamps are damaged ) = ( 4 / 10 ) * ( 3 / 9 ) = 12 / 90

P ( both lamps are damaged ) = 12 / 90

Hope this will help you. Thank you :)