A bag contains seven red balls numbered 2, 4, 5, 6, 7, 8, 10 and three white balls numbered 1, 3, and 9. If a ball is drawn, what is the probability the ball is red or even?

Answer 1

The probability of drawing a red ball is 7/10

The probability of drawing an even ball is 5/10.

However, you must subtract those balls that are both red AND even or else you are counting them twice.

The probability of drawing a ball that is red AND even is 5/10.

7/10 + 5/10 - 5/10 = 7/10