In our example let the 5 people be A B C D and E. How many different combinations of 2 prizes could you possibly choose. C nr n r.
Hence the number of possible outcomes is 2.
You look at the As and say yes or no. You look at the As and say yes or no. To calculate combinations we will use the formula n C r n. So the above equation expresses the number of ways for picking r unique unordered outcomes from n possibilities.