Multiple choice

A man wears socks of 2 colours - black and brown. He has 20 black socks and 20 brown socks in a bag. Suppose that he has to take out the socks in the dark. How many must he take to ensure that he has a matching pair?

  1. 3

  2. 4

  3. 11

  4. 21

  5. 31
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In the worst case scenario: the first 2 socks that the man picks can be of different colours, i.e. one brown and one black. Now, the 3rd sock that he picks will be either be brown or a black that will pair with one of the 1st two socks. Hence, upon drawing 3 socks, he will get a pair.

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