Question

A survey of 140 pet owners yielded the following information: 47 own fish; 53 own a bird; 50 own a cat; 68 own a dog; 2 own all four; 11 own only fish; 14 own only a bird; 10 own fish and a bird; 21 own fish and a cat; 26 own a bird and a dog; 29 own a cat and a dog; 3 own fish, a bird, a cat, and no dog; 1 owns fish, a bird, a dog, and no cat; 9 own fish, a cat, a dog, and no bird; and 10 own a bird, a cat, a dog, and no fish. How many of the surveyed pet owners have no fish, no birds, no cats, and no dogs? (They own other types of pets.)

Answer 1

18

Explanation:

This is venn diagram with 4 elements

Fish = n(F)

Bird = n(B)

Dog = n(D)

Cat = n(C)

The formula is given as

n (F ∪ B ∪ C ∪ D) - n(pet owners that have not fish, bird, cat or dogs) = n(F ) + n ( B ) + n (C) + n(D) - n ( F ∩ B) - n ( F ∩ C) - n ( F ∩ D) - n ( D ∩ B) - n ( D ∩ C) - n ( C ∩ B) + n(F ∩ D ∩ C) + n(F ∩ D ∩ B) + n(F ∩ C ∩ B) + n(D ∩ B ∩ C)- n (A ∩ B ∩ C ∩ D)

= 140 - n(pet owners that have not fish, bird, cat or dogs) = 47 + 53 + 50 + 68 - 21 -26 - 29- 10 - 2

140 - n = 218 - 88

140 - 218 - 88 +[(9 + 4 + 10) -(11 + 14)] = n

140 - 218 - 88 + (33 - 25)= n

140 - 130 + 8 = n

10 + 8 = n