A bag has 7 red balls, 4 yellow balls, and 9 green balls. What is the probability that two balls picked randomly are both the same color?
+23245 There are 7 + 4 + 9 = 20 balls altogether.
You can pick two balls of the same color if you:
1) pick two red balls: (7/20) x (6/19) = ........
2) pick two yellow balls: (4/20) x (3/19) = ......
or
3) pick two green balls: (9/20) x (8/19) = ........
You'll need to do the three individual calculations and add their answers together ...
