Question

3. A bag has 6 blue balls, 8 red balls, 5 black balls and 9 white balls. You are asked to pick some

balls from the bag, without looking into the bag. What is the minimum number of balls you

must pick so as to be sure that at least 3 of them are of the same color?

a) 5 b) 8 c) 9 d) 11

Answer 1

No. of blue balls = 6
No. of red balls = 8
No. of black balls = 5
No. of white balls = 9

We have to pick some balls under a condition of at least 3 of the balls are of the same color. 
For first four picks
red, white, black, blue

For next four picks
white, red, blue, black

For next one pick
If we get any color then the condition is satisfied that we get at least of 3 same colored balls.

So, the minimum no.of balls are 4+4+1 = 9.
The answer is 9.


Hope this helps you.