In a survey of 400 students, 100 were listed as drinking apple juice, 150 as drinking orange juice and 75 were listed as drinking both. How many students were drinking neither apple juice nor orange juice?
Answer: C
Let A be the set for apple juice and O for orange juice.
n(A) = 100, n(O) = 150, n(A ∩ O) = 75.
Number of students drinking at least one juice = n(A ∪ O) = n(A) + n(O) - n(A ∩ O) = 100 + 150 - 75 = 175.
Total students = 400.
Number of students drinking neither = Total - n(A ∪ O) = 400 - 175 = 225.