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

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 20 are excluded, the average mark of the remaining will be 92. Find the number of students who wrote the exam.

## Quiz

30

### Steps/Work

Let the number of students who wrote the exam be x.
Total marks of students = 80 x.
Total marks of (x - 5) students = 92(x - 5)
80x - (5 * 20) = 92(x - 5)
360 = 12x => x = 30

## General Calculator / Auto Solver

The average mark of the students of a class in a particular exam is . If students whose average mark in that exam is are excluded, the average mark of the remaining will be . Find the number of students who wrote the exam.

30

### Step by Step Solution

In order to solve problem, you must evaluate (n1 * n3 - n1 * n2) / (n3 - n0).

 n0 = 80 5 20 92
• (n1 * n3 - n1 * n2) / (n3 - n0)
• Evaluate n1 * n3 = 460

(460 - n1 * n2) / (n3 - n0)
• Evaluate n1 * n2 = 100

(460 - 100) / (n3 - n0)
• Evaluate 460 - 100 = 360

360 / (n3 - n0)
• Evaluate n3 - n0 = 12

360 / 12
• Evaluate 360 / 12 = 30

30
• The answer to the problem and the result of (n1 * n3 - n1 * n2) / (n3 - n0) is 30