Question

A box contains 6 red, 3 white, 2 green, and 1 black (in total 12) identical balls. What is the least number of balls necessary to take out randomly (without looking) to be sure of getting at least two white balls?

Answer 1

Pick at least 4 balls to be sure that you are getting balls with the same color.

Explanation:

Here, you want to know the least number of balls to be taken out of the box to be sure that you have all the three colors represented.

You know there are 12 identical balls, with the least numbers of balls being 1 and 2. Hence, to be able to know you have all the colors of balls represented, you will need to have taken all the less represented ones i.e the 1 and 2 , and this means that the next number of ball which would be taken will confidently confirm that you have taken all the colors since you would have exhausted picking other balls at this point.

So you shall be needing at least 4 balls picked to ensure that you have all the colors represented