Question

In a class of students, the following data table summarizes how many students play an instrument or a sport. What is the probability that a student who plays a sport also plays an instrument?
Plays an instrument Does not play an instrument
Plays a sport 4 7
Does not play a sport 2 8

Answer 1

We want P(plays instrument | plays sport) = (number who play both) / (number who play a sport) = 4 / (4+7) = 4/11 ≈ 0.3636 (36.36%).