Bunuel wrote:

There are 68 children in the cafeteria of a school and all of the children have something for lunch. Thirty-four of the children brought lunches from home, 23 of the children bought a drink from the cafeteria beverage machine, and 32 of the children bought fruit in the cafeteria. If 18 children did at least 2 of these things, how many children did exactly two of these things?

A. 3

B. 6

C. 9

D. 13

E. 15

We can use the following formula:

Total = n(L) + n(D) + n(F) - n(exactly two) - 2 * n(all three) + n(none)

68 = 34 + 23 + 32 - x - 2 * (18 - x) + 0 [Note: n(all three) = n(at least two) - n(exactly two)]

68 = 89 - x - 36 + 2x

68 = 53 + x

x = 15

Answer: E

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Scott Woodbury-Stewart

Founder and CEO

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