Q: The number of ways in which a mixed double game can be arranged amongst 9 married couples if no husband and wife play in the same game is
(C) 2 . 9C27C2
(D) none of these
Sol. We can choose two men out of 9 in 9C2 ways. Since no husband and wife are to play in the same game, two women out of the remaining 7 can be chosen in 7C2 ways.
If M1, M2, W1 and W2 are chosen, then a team may consist of M1 and W1 or M1 and W2. Thus the number of ways of arranging the game is
(9C2) (7C2)(2) = 1512.
Hence (B), (C) are the correct answer.