Question

A bag contains 5 red balls and 3 blue balls. A ball is picked at random from the bag and not replaced. Another ball is then picked at random.

What is the probability that the balls will be the same colour?

Answer 1

• 13/28

Explanation:

Given

• 5 red ball
• 3 blue ball

8 total balls

• p(r and r) = 5/8*4/7 = 5/14
• p(b and b) = 3/8*2/7= 3/28

Added up

• 5/14 + 3/28 = 10/28 + 3/28 = 13/28

Probability of 2 same colored balls is 13/28