In a class, 18 students play cricket, 12 play football, and 5 play both. How many students play at least one game?
Answer and explanation
Correct answer: 25
Let C be the set of cricket players and F the set of football players. Students who play at least one game belong to C ∪ F. By the inclusion–exclusion formula, n(C ∪ F) = n(C) + n(F) − n(C ∩ F) = 18 + 12 − 5 = 25. The five students who play both were counted twice, so they must be subtracted once.
Frequently asked questions
What is the correct answer to this question?
25
Why is this the correct answer?
Let C be the set of cricket players and F the set of football players. Students who play at least one game belong to C ∪ F. By the inclusion–exclusion formula, n(C ∪ F) = n(C) + n(F) − n(C ∩ F) = 18 + 12 − 5 = 25. The five students who play both were counted twice, so they must be subtracted once.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Sets. Topic: Operations on Sets (Union, Intersection, Difference).