Question

There are 20 students in a class. The average marks of first 10 students is 56. The average marks of remaining students is 46.5. Find the average marks of whole class.
1. 50
2. 55.25
3. 51.25
4. 53

Answer 1

Correct Answer - Option 3 : 51.25

Given

Total students in a class is  20

Average of first 10 students is 56 while remaining is 46.5

Formula used

Average = total sum of observations/number of observations

Calculation

Number of students in class = 20

⇒ Total sum of marks of first 10 students = 56 × 10

⇒ 560

⇒ Total sum of marks of  remaining students = 46.5 × 10

⇒ 465

⇒ Total marks of students in class = 560 + 465

⇒ 1025

⇒ Average = 1025/20

∴ Average marks of students in the class is 51.25