Arithmetic Ability
Permutations and Combinations

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Q.

A Group consists of 4 couples in which each of the  4 persons have one wife each. In how many ways could they be arranged in a straight line such that the men and women occupy alternate positions?

View Answer

Correct choice: A

Explanation:

Case I : MW MW MW MW Case II: WM WM WM WM Let us arrange 4 men in 4! ways, then we arrange 4 women in 4P4 ways at 4 places either left of the men or right of the men. Hence required number of arrangements 4! × 4P4 + 4! × 4P4 = 2 × 576 = 1152
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