An urn contains 8 white and 3 red balls.if two ball are drawn at random, find the probability of both are white,both are red and one is of each colourr

Question

An urn contains 8 white and 3 red balls.If two balls are drawn at random . Find the probability of both are white,both are red, and one is of each colour

Answer 1

P(both White) = 8/11 x 7/10 = 56/110 = 28/55

P(both red) = 3/11 x 2/10 = 3/55

P(1W&1R) = 8/11 x 3/10 + 3/11 x 8/10 = 24/110 + 24/110 = 48/110 = 24/55

To check your answer, sum up the 3 probabilities: 28/55 + 3/55 + 24/55 = 55/55 = 1

they exhaust all possible outcomes, so their sum must = 1 = certainty.

It's certain you'll get one of the 3 possibilities.