SOLUTION: Your drawer contains 10 red socks and 7 blue socks. It is too dark to see which are which, but you grab two socks anyway. What is the probability that both socks are blue?

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Question 1113735: Your drawer contains 10 red socks and 7 blue socks. It is too dark to see which are which, but you grab two socks anyway. What is the probability that both socks are blue?
Answer by ikleyn(52776) About Me  (Show Source):
You can put this solution on YOUR website!
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The total set of events is the set of all pairs of socks  {(sock,sock)}  independently of their color.


You have 10+7 = 17 socks in all;  therefore, you have  %2817%2A16%29%2F2 = 136 pairs.



Of them, the favorable set is the set of all pairs of blue socks, and the number of such pairs is  %287%2A6%29%2F2 = 21.


Therefore, the probability under the question is  21%2F136.

Solved.