math
posted by clay .
How many ways can a person select four books, two CDs, and one DVD from ten books, twenty CDs, and five DVDs?

To handle this type of question, my must be familiar with the C(n,r) notation.
The person can select the books in C(10,4) or 210 ways
the CD's in C(20,2) or 190 ways
and the DVD's in C(5,1) or 5 ways.
So the number of ways to make the selection is
210*190*5 ways or 199500 ways.