Question

the average marks of each sections with 30,45,52 students are 30,45.41 respectively. What is the average marks of of all the section combinedly

Answer 1

Avg marks of 30 students = 30
So sum of marks of all the students = 900

Avg marks of 45 students = 45
So sum of marks of all the students = 2025

Avg marks of 52 students = 41
So sum of marks of all the students = 2132

Thus,
Total Students = 127
Total Marks = 5057

So,
Avg Marks = 5057 / 127 = 39.8188976

Answer
39.8188976

Answer 2

Average of all sections =  total marks in all sections / total number of students
           = [ 30 * 30 + 45 * 45 + 52 * 41 ] / [30 + 45 + 52 ]
           = 39.82    rounded to 2nd decimal place