There are 50 students in a class. The average marks of 20 students is 70 and the remaining 30 have average marks of 80. Calculate the average score of the whole class.

Correct option is C

Given:

Total strength of class = 50

Average marks of 20 students is 70

Average marks of remaining 30 is 80

Formula Used:

Average =$$\frac{Sum\ of\ observations}{Number\ of\ observations}$$​​

Solution:

Total marks of 20 students is 20 $$\times$$​70 = 1400

Total marks of 30 students is 30 $$\times$$​ 80 = 2400

Total marks of whole class = 1400+2400 = 3800

Average marks =$$\frac{3800}{50} =76$$​​