yogeshsheth
FIG could you please expalin the above solution in detail..
Thanks!!
At least, I can try
We are looking for the number of possible matches, thus the order does not matter.
We can consider a "first" couple. The husband or the wife, 1C2, can play against a wife or a husband, 1C2, of 1 of the 6 other couples, 1C6.
Thus, the "first" couple could play : 1C2*1C6*1C2 matches.
Then, we can consider a "second" couple. One more time, The husband or the wife, 1C2, can play against a wife or a husband, 1C2, of 1 of the 5 remaining other couples, 1C5.
Thus, the "second" couple could play : 1C2*1C5*1C2 matches.
The patern indicates that we decrease the remaining number of couple.
And so on... till we arrive at couple 6 that can play only the wife or husband of the latest couple.
Hence, we sum up all these matches:
Sum = 4*(6+5+4+3+2+1) = 4*21 = 84.