probability

[Maureen offline]

How many ways can a person select 4 books, 2 CD's, and 1 DVD, from 10 books, 20 CD's, and 5 DVD's?

I think the equation is nPr=n!/(n-r)! Not sure what to subsitute for variables.

[Viper offline]

The formula is correct for combinations; Problem is, this involves permutations.

[Viper offline]

N is the number, and in this case, it is 35, I believe. R is the rate u take it at. This would be 7. Now, it would be 35P7. Exclamation marks hint at factorials. This would mean 28x27x26, etc. But irregardless, this is useless as I said this is permutations, not combinations..