Question

There is 10 green marbles and 10 blue marbles in a bag. What is the minimum number of marbles you need to pull out of the bag to be 100% sure that you have two marbles of the same color without looking at the marbles

Answer 1

3

Step-by-step explanation:

3 see below.

Take a much much easier problem that you might actually encounter in your life.

Suppose you have a sock drawer in your room that you haven't had the energy to put in order. Suppose you only look at that drawer when it is pitch black in the room. There are only 2 color socks in there -- red and green. How many socks to you have to pull out to assure that you have 2 of one color when you pull them out.

No cheating!

Three right. Suppose you pull out 1 green and 1 red. The next sock you pull out will have to be one of those 2 colors, right?