Question

Four out of 9 performers will be chosen to stand in a row on stage. How many ways can the 4 performers stand in a row?   A. 362,880 ways   B. 347,760 ways   C. 15,120 ways   D. 3024 ways

Answer 1

Imagine you have 4 'slots' on the stage:
_ _ _ _

In the first one there can be 1 out of 9 performers.
In the second - 1 out of 8 (because one has been already chosen).
In the third - 1 out of 7 (because two have been selected).
In the forth - 1 out of 6 (because three are already on the stage).

Total number of combinations is equal to: 9x8x7x6 = 3024

So the correct answer is D.

Hope it helps!