In a bird sanctuary 41 different special of birds are being studied. Three large bird feeders are constructed, each providing a different type of bird feed. One feeder has sunflower seeds. A second feeder has a mixture of seeds, and the third feeder has small pieces of fruit. The following information was obtained.

Question

20 species ate sunflower seeds
22 species ate the mixture
11 species ate the fruit
10 species ate the sunflower seeds and the mixture

4 species ate the sunflower seeds and the fruit
3 species ate the mixture and the fruit
1 species ate all three.

• How many species ate
– A. None of the foods
– B. The sunflower seeds, but neither of the other two foods?
– C. The mixture and the fruit, but not the sunflower seeds?
– D The mixture or the fruit, but not the sunflower seeds?
– E. Exactly one of the foods?

Answer 1

A. 23
B. 20
C. 3
D. 33
E. 53