In a class of 50 students, 30 take Mathematics, 25 take Biology and 15 take both Mathematics and Biology. How many students take neither Mathematics nor Biology?
In a class of 50 students, 30 take Mathematics, 25 take Biology and 15 take both Mathematics and Biology. How many students take neither Mathematics nor Biology? Correct Answer 10
Given:
The total number of students in a class = 50
The number of students takes Mathematics = 30
The number of students takes Biology = 25
The number of students take both Mathematics and Biology = 15
Formula used:
n(A ∪ B) = n(A) + n(B) - n(A ∩ B)
n(A ∪ B)' = n(U) - n(A ∪ B)
where, n(A) = number of elements in A, n(B) = number of elements in B
n(A ∩ B) = number of elements in both A and B, n(A ∪ B) = number of elements in either A or B
n(U) = number of total students
Calculation:
Let the set of total students be U, the set of students takes Mathematics be A
And the set of students takes Biology be C.
According to the question,
n(U) = 50, n(A) = 30, n(B) = 25 and n(A ∩ B) = 15
Now, students take either Mathematics or Biology = n(A ∪ B)
⇒ n(A) + n(B) - n(A ∩ B)
⇒ 30 + 25 - 15
⇒ 40
So, students take neither Mathematics nor Biology = n(A ∪ B)'
⇒ n(U) - n(A ∪ B)
⇒ 50 - 40
⇒ 10
∴ The students take neither Mathematics nor Biology is 10.