October 11, 2016

Problem No. 10. Socks in a drawer

You have 7 pairs of black socks in your drawer, among 30 pairs in total. The rest of them are white socks. What is the smallest number of socks you should take out from the drawer (with your eyes closed) to be sure that you have a matching pair of white socks?

Parent tip

You can give this problem during the house chores. It is the fun way to implement the mathematical thinking outside the classroom. Children should know that math is real, fun and useful.












Solution

You should take out 16 socks to be sure that you have a matching pair of white socks, since you may have taken out all 14 black socks, so the next 2 socks will be white for sure.

Additional question

How many socks should you take out from the drawer to be sure that you have a matching pair of white socks, if all white pairs of socks are different?

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