Determine the Appropriate Counting Technique to Use
-In how many ways can Iris choose 4 of 9 books to bring on vacation?
A) 126
B) 3024
C) 24
D) 6561

Question

Quizplus · Accepted Answer

This is a combination problem because the order in which Iris chooses the books does not matter. The formula for combinations is C(n, k) = n! / [k!(n - k)!], where n is the total number of items to choose from, and k is the number of items to choose. Here, n=9 and k=4, so C(9, 4) = 9! / [4!(9 - 4)!] = 126.