8th Math Riddles 2019

Probability Level 1

You have 14 brown socks, 14 blue socks and 14 black socks randomly placed in your sock drawer. What is the maximum number of socks you must take out from the drawer to be 100% guaranteed that you get a matched pair?

2 3 1 4 7 6 5 0

Rui Chang Lu by Rui Chang Lu , 15, Oman

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2 solutions

Chew-Seong Cheong
Jan 22, 2019

Since there are only 3 different colors of socks. The greatest number of socks of different colors you can remove from the drawer is 3. The 4 \boxed 4 th one you draw will be the same color with at least one of the other 3.

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Hey how are you again. I just wanted to tell you that one person called "Brian Charlesworth" who reported my "8th Math Riddle 2019". I don't think that he is very fond of my riddle question, may you please check the report and resolve it if it is necessary or tell me so I can delete my problem? Thanks again!

Rui Chang Lu - 2 years, 4 months ago

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He does not mean bad. He just wanted to clarify to that the phrasing is not very clear so as not to mislead other members and also you can change it. It is a usual process in Brilliant. I have changed the phrasing for you.

Chew-Seong Cheong - 2 years, 4 months ago
Jordan Cahn
Jan 22, 2019

By the pigeonhole principle , once you've removed four socks, you must have at least two of the same color, forming a pair.

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