Question

A bag contains 20 balls. 8 balls are green, 7 are white and 5 are red. what is hie minimum number of balls that must be picked up from the bag blindfolded (without replacing any of it) to be assured of picking at least one ball of each colour?

Answer 1

There are 8 balls that are green and 7 that are white.Now,if we pick 8 + 7 = 15 balls,there remains a chance that 8/8 are green and 7/7 are white,that is all 15 are green and white.Now,if we pick 15+1 = 16 balls,there cannot be more than 15 balls that are green and white,so we will get at least 1 red ball.So,16 is the answer.