Question

the average mark of the students of a class in a particular exam is 80.if 5 students whose average mark in that exam is 40 are shifted to another class the average mark of the remaining would be 90.find the number of students who wrote the exam

Answer 1

the answer of your question is 130

Answer 2

Answer:

25

Step-by-step explanation:

Let the number of students who wrote the exam be x.

The average mark of the students of a class in a particular exam is 80

$80=\frac{\text{total marks of class}}{x}$

Total marks of  students = 80x.

5 students whose average mark in that exam is 40 are shifted to another class

$40=\frac{\text{total marks of shifted students}}{5}$

$200=\text{total marks of shifted students}$

Sum of marks of remaining students = 80x-200  --A

The average mark of the remaining would be 90

$90=\frac{\text{total marks of remaining students}}{x-5}$

$90(x-5)=\text{total marks of remaining students}$  ---B

Equate A and B

$80x-200=90(x-5)$

$80x-200=90x-450$

$450-200=90x-80x$

$250=10x$

$25=x$

Hence the number of students is 25