Question 1113735
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<pre>
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  {{{(17*16)/2}}} = 136 pairs.



Of them, the favorable set is the set of all pairs of blue socks, and the number of such pairs is  {{{(7*6)/2}}} = 21.


Therefore, the probability under the question is  {{{21/136}}}.
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Solved.