Question 577913
To find the cumulative (total) average of all students, we simply multiply each class average by the number of students, add the 2 sums together, and divide by the total number of students.

total students = 80 + 40 = 120 students

cumulative average = sum(class1 and class 2) / 120 students

= (80x30 + 40x50) / 120
= (2400 + 2000) / 120
= (4400) / 120
=36.6666666666666666 = 36 2/3