m not sure if this is the right section to post permutation problem, but anyways please help me out with the following
In how many ways can 10 soldiers stand in 2 rows such that there are 5 soldiers in each row?
Is the answer 7257600 or 7257600/2 ?
October 25th 2009, 07:10 PM
There is no way the answer is 7 million. Now what I did may be wrong, but I know 7 million can't possibly be right.
You have 10 soldiers. For the first row you are told out of the 10 soldiers, to order 5 that will be placed in it (as order matters, not uniqueness - since you are asked the number of WAYS the soldiers can placed): 10P5. In the second row you have 5P5 ways of arranging the remaining soldiers. Therefore (10P5) + (5P5) = Number of ways to arrange 10 soldiers in two rows.