Question 1150914
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            In this problem, we consider and count only unordered pairs of socks.



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(a)   {{{C[10]^2}}} = {{{(10*9)/2}}} = 5*9 = 45  ways.      <U>ANSWER</U>



(b)   6*4 = 24  ways.                     <U>ANSWER</U>



(c)   It can be computed in 2 ways.


          1)  Having the numbers from (a) and (b), everybody can easily conclude 

              that the answer for (c)  is the difference  45 - 24 = 21  ways.



          2)  Another way to compute it is this :   {{{C[6]^2}}} + {{{C[4]^2}}} = 15 + 6 = 21.

              Surely, it gives the same answer.
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Solved.



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