The means of marks secured by 25 students in section A of Class X is 47 that of 35 students of ...........

Quantitative Aptitude ( CCS) Average

The means of marks secured by 25 students in section A of Class X is 47, that of 35 students of section B is 51 and that of 30 students of section C is 53. Find the mean of marks of the students of three section of class X.

50.6

52.5

54.5

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Explanation:

Given mean marks of 25 students of class X section A = 47
Recall that, Sum of observations = Mean × Number of observations
Sum of marks of class X section A = 47 × 25 = 1175
Given mean marks of 35 students of class X section B = 51
Sum of marks of class X section B = 51 × 35 = 1785
It is also given that mean marks of 30 students of class X section C = 53
Sum of marks of class X section C = 53 × 30 = 1590
Sum of marks of all the students of A, B and C sections = 1175 + 1785 + 1590 = 4550
Hence mean of marks scored by 90 students = 4550 / 90 = 50.6

Hence, option 2 is the correct answer.