Page 45 - NUMINO Challenge_C2

5 Principle of Drawers

Basic Concepts The Unluckiest Case and the Luckiest Case

You want to pick out a pair of the same socks from a drawer that contains
two different pairs of socks. The follow shows the number of socks to pick
out in the lucky and unlucky cases.

Lucky case:

1st 2nd 1st 2nd

or

Unlucky case:

1st 2nd 3rd 1st 2nd 3rd

or

Therefore, you must pick out at least three socks to be sure to get a
matching pair.

Example There are three types of socks in a drawer: red, yellow, and blue.
Without looking in the drawer, how many socks must you pick out
Class Notes to be sure to get a matching pair?

If you are unlucky, you will pick out of each sock. In this case, the number of socks

is 1 1 1 .

In , if you pick out more sock(s), you will always have socks with the same
colors.

Therefore, you must pick out at least 3 1 socks to be sure to get a matching pair.

42 NUMINO Challenge C2