Sarah has 5 friends who are available to go with her to the movies, but she only has

3 extra tickets. How many different choices does Sarah have for which 3 friends to invite.

10 different choices

Step-by-step explanation:

This is a combination problem: we need to make groups of 3 people among 5 people, and the order of the people inside a group doesn't matter (does not make a different group).

If the total number of people is 5 and we need groups of 3, this is a combination of 5 choose 3:

C (5,3) = 5! / (3!*2!) = 5*4/2 = 10

Sarah has 10 different choices