Question

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

Answer 1

Ans: 16.

Explanation:

Here mentioned 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, answer will be 16 balls.

Hope This Helps :)