Question 3 | BetaMath

Question 3

Students from 4 different schools come together to form a choir.

What is the minimum size of the choir to know that there must be at least 20 students in the choir from one of the schools?

A. 76

B. 77

C. 80

D. 81

Solution

If we can calculated the largest possible group that does not have 20 students from any school, then we can be certain there are at least 20 students from a single school if we see a group bigger than this.

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