Question

The average marks of 65 students in a class was calculation as 150 it was later realise that the mark of one of the students calculators 142 where sa his actual mark was 152 calculate the actual average mark of the group of 65 students

Answer 1

Total marks of 65 students = 150 x 65 = 9750

Total marks of 19 students after removing wrong marks = 9750 - 142 = 9608

Total marks of 20 students after correcting = 9608 + 152 = 9760

Actual average mark of the group of 65 students = 9760 ÷ 65 = 150.15

Answer 2

Answer:

Actual Average marks of the group of 65 students is 150.15

Step-by-step explanation:

Given: Number of student = 65

          Average marks of Students = 150

          Wrong mark includes = 142.

          Correct marks = 152

To find: Actual/correct Average.

Let x be the sum of correct marks of 64 students other than wrong mark.

According to the question,

$\frac{x+142}{65}=150$

$x+142=150\times65$

x + 142 = 9750

x = 9608

Now, Actual Average = $\frac{x+152}{65}=\frac{9608+152}{65}=\frac{9760}{65}=150.15$

Therefore, Actual Average marks of the group of 65 students is 150.15