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Interview prep / Brainteaser/Logic

Blind draws to guarantee a matching pair of socks

Question

A drawer contains 88 red socks and 1111 blue socks. Without looking, how many socks must you take out to be certain you have two of the same colour?

Short answer

3. With only two colours, any three socks must include two of the same colour by the pigeonhole principle, while two socks could be one of each.

Adapted from Crack, Heard on the Street, Q1.15, p.12; question and answer rewritten by SelfMadeQuant.com.

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