Question

Michael is packing his bags for his vacation. He has 6 unique books, but only 4 fit in his bag. How many different groups of 4 books can he take?

Answer 1

Answer:

15

Step-by-step explanation:

Michael has 6 unique books, but 4 not-unique slots. Since the slot is not unique, the orders you pick the 4 books are not important. When order important you use permutation but since the order is not important you use the combination. The calculation will be:

6C4 = $\frac{6!}{6!(6-4)!}$ = 15

There are 15 ways to group the 4 books.