We don't need a lot of fancy formulas . . .
There are: . possible choices.A casting for a play is being held at the local high school's gymnasium.
There are a total of 20 actors of differing age groups that attended this casting call;
they included 5 children, 7 adults, and 8 seniors.
There are only 3 acting roles available for the play and the casting director
decided to fill these roles by randomly drawing 3 of the 20 actors' name from a box.
Assuming all 3 acting roles in the play are different, what is the probability
that 3 actors of the same age range were chosen for the play?
3 children: . ways.
3 adults: . ways.
3 seniors: . ways.