Question

The marks of a student were entered as 88 instead of 68. Due to this, the average marks of the class increased by 0.5. What is the number of students in the class?
1. 10
2. 20
3. 30
4. 40

Answer 1

Correct Answer - Option 4 : 40

Given:

One student marks were entered 88 instead of 68

Average of the students increased by 0.5

Formula used:

Average = Sum of marks of all the students/Total number of students

Calculation:

Let the total number of students in the class be n

Let the sum of the marks of the students except the wrong entered be x

The Original sum of marks of the students = x + 68

The sum of the marks of the student after wrong entered = x + 88

Now, A/Q

(x + 88)/n – (x + 68)/n = 0.5 

⇒ (88 – 68)/n = 0.5

⇒ 20/n = 0.5

⇒ n = 40

∴ The total number of students in the class is 40.