Question

 The average of marks obtained by 65 students in maths is 54. Due to some error while typing the marks of one student were mis printed as 87 instead of 78. Find the average marks after rectifying the mistake.
1. 53.86
2. 54.12
3. 84.32
4. 55.33

Answer 1

Correct Answer - Option 1 : 53.86

Given:

The average of marks obtained by 65 students in maths is 54. Due to some error while typing the marks of one student were mis printed as 87 instead of 78. 

Concept used:

Average

Calculation:

Due to some error while typing the marks of one student were mis printed as 87 instead of 78. 

Difference of marks = 87 - 78 = 09 marks

Average marks of 65 students = 54 marks

Correct average = \(54 - \frac{9}{{65}}\)

Correct average = 53.86

Second method:

In this you can directly mark the answer through the options

Due to some error while typing the marks of one student were mis printed as 87 instead of 78. 

Difference of marks = 87 - 78 = 09 marks

Average marks of 65 students = 54 marks

Correct average = \(54 - \frac{9}{{65}}\)

Here the answer will be always less than 54

Only option A has value less than 54 

Ans : 53.86