Jenna is at a fair with four friends. They all want to ride the roller coaster, but only three people can fit in a car. How many different groups of three can the five of them make?
To answer this question, I need to count how many ways I can choose three people out of five, without regard to the order of the people in the group. This is a combination problem, and I can use the formula for the number of combinations of n objects taken r at a time: nCr = n! / (r! (n - r)!), where ! means factorial. In this case, n = 5 and r = 3, so I plug these values into the formula and simplify: 5C3 = 5! / (3! (5 - 3)!) = 120 / (6 * 2) = 120 / 12 = 10. Therefore, there are 10 different groups of three that the five friends can make. 