| 1. |
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?1. 52. 103. 154. 20 |
|
Answer» Correct Answer - Option 2 : 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. |
|