Need help with probabiltiy?

First, you have to know how many there are in total. There are 15 B , 15 I , 15 N , 15 G , and 15 O . That means there are 75 balls in total. Since there are 15 G balls, the chance that the ball selected is a G ball is 15/75 or 1/5. This means, the odds against it is 4/5 (1 - 1/5).