In how many ways can Iris choose 4 of 13 books to bring on vacation?
A) 715
B) 17,160
C) 24
D) 28,561

Question

Quizplus · Accepted Answer

The number of ways Iris can choose 4 out of 13 books is calculated using the combination formula, which is C(n, k) = n! / [k!(n-k)!], where n is the total number of items (13 books), k is the number of items to choose (4 books), and "!" denotes factorial. Thus, C(13, 4) = 13! / [4!(13-4)!] = 13! / (4!9!) = (13×12×11×10) / (4×3×2×1) = 715.

In How Many Ways Can Iris Choose 4 of 13