Socks in a drawer

3.5 stars

There are 30 socks in a drawer. 60% of the socks are red and the rest are blue. What is the minimum number of socks that must be taken from the drawer without looking in order to be certain that at least two blue socks have been chosen?

See below for answer


20 socks

 

Difficulty
  • Moderate
Type
  • Mathematical
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Comments

6 (i think)
- kitty (25 May 2009)

Since there are 18 (60%) red socks, you would have to pick 20 socks to be certain that you have at least 2 blue socks.
- tom (30 Jun 2009)

60% of 30=18 (red), Therefore pick up minimum 20 socks without looking in order to be certain that the least two blue socks have been chosen.
- Nan Nwe Nwe (28 Jul 2009)

since there are 12 blue socks, one would need to pick out a minimum of 13 socks.
- ron (13 Oct 2009)

3.

Since their are only two possible colors, red or blue, picking three would guarantee at least two of the same color.
- Andrew (16 Dec 2009)

Why is it that Ron and Andrew have answered totally wrong, when the answer is printedm and Tom and Nan Nwe Nwe are so spot on? Also Andrew, it clearly says 2 BLUE socks, not 2 of any colour
- Dave (5 Mar 2010)

Why is kitty so stupid?

- Rico (12 Apr 2010)

Assuming that the drawer is not well mixed, like most normal people, just 2 draws would be necessary seeing as one would know where the blue socks are located.
- Ryan (26 Apr 2010)

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