Suppose that the number of men's pair, women's pair = number = n
1 pair men will see that there is a man and 2 man
. The pair are the first pair of men to join 2 is 4 people
. The couple had 3 sons, in combination with the second pair is 6 people
.... .... So the couple, there are n male to double n-1 is 2n
people. Similarly, for women, there are n couple girls with girls double n-1 is 2n
people. Therefore, in all the men who have switch 2n (2n)! for girls who have switched 2n
(2n)! People as well. In addition, for a group of men and women's groups to switch a 2 x
2 method (2n)! x (2n)! = 1152
(2n)! = 576 2
(2n)! = 24 = 4
4
n! = 2n = 2
that is, men and women are each 2 pair (a total of 8 people)
. Anyway, Select men and women coming out each 2 people stand in a straight line by, men stand on the switch woman
. The number of how many men, how to select Select = women = 6 ways
. Therefore, the number of ways to stand in a straight line by a man-woman standing alternately. = 6 x 6 x 2 = 72 ways
.
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