A group of campers is going to occupy 4 campsites at a campground. There are 15 campsites from which to choose. In how many ways can the campsites be chosen?

Step 1 ：A group of campers is going to occupy 4 campsites at a campground. There are 15 campsites from which to choose. In how many ways can the campsites be chosen?

Step 2 ：We can solve this problem using the combination formula, which is given by \( C(n, k) = \frac{n!}{k!(n-k)!} \), where \( n \) is the total number of items, \( k \) is the number of items to choose, and \( ! \) denotes factorial.

Step 3 ：Here, \( n = 15 \) and \( k = 4 \).

Step 4 ：Substituting these values into the formula, we get \( C(15, 4) = \frac{15!}{4!(15-4)!} \).

Step 5 ：Calculating the factorials and simplifying, we find that the number of ways the campers can choose 4 campsites out of 15 is \(\boxed{1365}\).