Question

A pizza parlour sells 12 different pizza toppings.

Grace orders a pizza with 3 different pizza toppings.
How many different pizzas can Grace order?

Include any equations and working out used.

Answer 1

Explanation:

so, we pick 3 out of 12.

they are 3 different picks, so there are no repetitions.

the sequence does not matter, as clearly e.g. ham, bacon, onion is the same as onion, bacon, ham.

so, we have combinations without repetitions :

C(12, 3) = 12! / (3! × (12-3)!) = 12! / (3! × 9!) =

= 12×11×10 / 3×2 = 4×11×5 = 220

she can order 220 different pizzas.