Question

A pizza parlor advertises pizza options. They offer 7 toppings and allow up to 4 on each pizza. Write an expression that represents this situation.
A: 7!
B: 7!/3!
C: 7!/4!3!
D: 4!3!/7!

Answer 1

Answer:  Choice C

Explanation:

This is after using the nCr combination formula

$_n C _r = \frac{n!}{r!*(n-r)!}$

where in this case n = 7 and r = 4. Note how n-r = 7-4 = 3.

We use nCr instead of nPr because the order of the toppings doesn't matter.