150 students are studying English, Maths or both. 62% study English and 68% study Maths. How many are studying both?
45 students
n(E) = 62% of 150 = 93, n(M) = 68% of 150 = 102.
Total = 93 + 102 − n(E ∩ M) = 150.
195 − n(E ∩ M) = 150 ⇒ n(E ∩ M) = 45.