Question

The manager of the various displays in the Acme Fine Clothing Emporium has a window which will hold 3 dummies. He has 10 dummies, each showing a different style outfit, from which to choose. How many different displays can he arrange in his display window? (If the order in which the dummies appear changes, it is regarded by the manager as`a different display.)

Answer 1

Is it 15,120?

Answer 2

You can read http://en.wikipedia.org/wiki/Permutations to understand this problem.
Ask yourself the following questions:
1) How many ways can the manager choose the first dummy?
2) After choosing the first dummy how many ways, can the manager choose the second dummy?
3) After choosing the first and the second dummy how many ways, can the manager choose the third dummy?
The answer to the first question is 10.
What is the answer to the remaing questions? What is the answer to the problem?