72% of the students of a certain class took Biology and 44% took Mathematics. If each student took Biology or Mathematics and 40 took both. The total number of students in the class was?
Correct Answer: 250
Explanation:
Let the total number of students be 100
Then, n(A ∩ B) = n(A) + n(B) - n(A ∪ B) = (72 + 44 - 100)% = 16%
Now,16% of N = 40
⇒ (16 x N) / 100 = 40
∴ N = (100 x 40) / 16 = 250
