A box contains 5 yellow balls, 3 blue, and 1 red ball. Two balls are drawn at random. Find the probability that the two balls have the same color.
+128406 Assuming that the balls are drawn sequentially........we can either draw two yelow balls or two blue balls
P( two yellow balls ) = 5/9 * 4/8 = 20/72 = 5/18
P(two blue balls) = 3/9 * 2/8 = 6/72 = 1/12
So.....the total probability is 5/18 + 1/12 = [10 + 3 ] / 36 = 13 / 36
Edited Chris' answer:
Assuming that the balls are drawn sequentially........we can either draw two BLUE balls or two yellow balls
P( two YELLOW balls ) = 5/9 * 4/8 = 20/72 = 5/18
P(two blue balls) = 3/9 * 2/8 = 6/72 = 1/12
So.....the total probability is 5/18 + 1/12 = [10 + 3 ] / 36 = 13 / 36
