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Stu Dent Gets Fired

This is one of my favorite set theory questions...



Stu Dent, a new survey intern, was excited to turn in the results of his survey for tabulation. At the local mall, he had asked 40 people about their cereal preferences: Wheat Berry, Oat Squares, or Sugar Puffs.

His tabulated results:

  • 23 said they ate Wheat Berry
  • 18 said they ate Oat Squares
  • 19 said they ate Sugar Puffs
  • 12 said they ate Wheat Berry and Oat Squares
  • 6 said they ate Oat Squares and Sugar Puffs
  • 7 said they ate Wheat Berry and Sugar Puffs
  • 2 said they ate all three cereals
  • 2 said they would not eat any of those cereals
Why was Stu fired?

 


Hint: Draw a Venn Diagram to represent the situation.

 


Solution Commentary: When everything is sorted out in a Venn Diagram, is 40 your total number of people accounted for?