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Class Distinction

Problem

Mr. Venn draws two large overlapping circles on the floor of the sports hall and labels them B and R. He asks all those students with brown hair to stand in the B circle and those that are right handed to stand in the R circle; if they have both brown hair and are right handed, they need to stand in the region where the two circles overlap.

When they return to the classroom he asks his class of thirty two students how many have brown hair: twenty seven put their hands up. He then asks how many students are right handed: twenty four raise their hands.

What is the minimum number of students that stood in the overlap?

Problem ID: 192 (11 Dec 2004)     Difficulty: 1 Star

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