Question

The Venn diagram shows the number of customers who have purchased different types of pets from a pet store, where C represents customers who have purchased cats, D represents customers who have purchased dogs, and F represents customers who have purchased fish.

Circles C, D, and F overlap. Circle C contains 15, circle D contains 21, and circle F contains 12. The overlap of C and F contains 2, the overlap of F and D contains 0, and the overlap of D and C contains 3. The overlap of all 3 circles contains 1. Number 14 is outside of the circles.

How many people are in the set C ∩ D?

4
6
36
38

Answer 1

C ∩ D includes those in the D∧C-only region (3) plus those in all three (1). So |C ∩ D| = 3 + 1 = 4.

Answer: 4.