You just got a free ticket for a boat ride, and you can bring along 3 friends! unfortunately, you have 5 friends who want to come along. how many different groups of friends could you take with you ?

This is combinatorics related question. We need to find how many different groups we can make. To find this we use formula:

Where:
n=number of groups
N=number of people to choose from
k=number of people that we choose

In our case we have:


To calculate this we use binomial formula:


We can make 10 different groups.