Question

Of 480 consumers polled, some purchase ice cream, some purchase frozen yogurt, and some purchase both. If 260 people polled purchase ice cream and 200 purchase both ice cream and frozen yogurt, how many people purchase frozen yogurt?

Answer 1

Assuming that of the 480, everybody had either ice cream or yogurt

number for ice cream --- A
number for yogurt ---- B

N( A or B) = N(A) + N(B) - N(A and B)
480 = 260 + N(B) - 200
N(B) = 420

confirm the answer is corrrect by making a Venn diagram.

Answer 2

n+260-200 = 480
n = 420

420 bought just yogurt