Question

Jason, Erik, and Jamie are friends in art class. The teacher randomly chooses 2 of the 21 students in the class to work together on a project. What is the probability that two of these three friends will be chosen?

Answer 1

Now THAT's a problem !
Lemme at it !  Outa my way !

The probability of picking two of the friends to work together is

             (the number of pairs of friends there are)
divided by
             (the total number of pairs that can be pulled out of 21 students).

The number of pairs of friends there are is  (3 x 2) / 2  =  3 pairs.

The total number of pairs that can be selected out of 21 students is

                                           (21 x 20) / 2  =  210 pairs.

The probability that the pair selected will be two of the friends is

                       3 / 210  =  1/70  =  about 1.43 %  (rounded)