Question

In class, students want to join sports. 15 people will join football, 24 people will join basketball, and 7 people will join both. How many people are there in the class?

(a) 19

(b) 82

(c) 64

(d) 30

This question was posed to me by my college director while I was bunking the class.

This key question is from Discrete Probability topic in chapter Discrete Probability of Discrete Mathematics

Answer 1

The correct choice is (d) 30

The explanation: There are 15 people who wish to join football, but 9 of those people also join basketball. By using the principle of inclusion and exclusion, we have: 15 people joining football + 24 people joining basketball – 9 people who will join both = 30 people total.