Among a universal set of 72 festival visitors, 39 visit the art stall, 31 visit the music stall, and

Question

Among a universal set of 72 festival visitors, 39 visit the art stall, 31 visit the music stall, and 14 visit both. Mei says, “39 plus 31 is 70, so only 2 visitors visit neither stall.” Explain the counting error.[1] Calculate the correct number who visit neither stall.[2]

Accepted Answer

(a) The 14 visitors in both sets are counted twice. (b) $16$

Diagnosing double counting

Diagnosing double counting

Solution:

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