Question

The average marks of a class of some students is 45. But when marks of two other students are included in a class then average marks of class remains same. Find the average marks of newly added two students.
1. 45
2. 40
3. 50
4. 35

Answer 1

Correct Answer - Option 1 : 45

Given:

Average of class = 45

Formula:

Average marks of class = Total marks of class / Number of students of class

Calculation:

Let number of students in a class be n.

Total marks of a class = 45n

Let total marks of two students be b.

Total marks of a class including two students = 45n + b

Total marks of class including two students = 45 × (n + 2)

⇒ 45n + 90 = 45n + b

⇒ b = 90

∴ Required average = 90/2 = 45

If average of n terms is x and m number of terms are included and the average after inclusion is same.

Then the average of newly included m terms is same (i.e. x)

Hence in this question we can say that the average marks of two new students is 45