Question 87

The mean of marks secured by 55 students in division-A of class X is 55, 45 students of division-B is 51 and that of 40 students of division-C is 49. What is the mean of marks of the students of three divisions of Class X?

Solution

Total marks secured by 55 students in division A = 55 $$\times$$ 55 = 3025

Total marks secured by 45 students in division B = 45 $$\times$$ 51 = 2295

Total marks secured by 40 students in division C = 40 $$\times$$ 49 = 1960

=> Mean of marks of the students of three divisions of Class X = $$\frac{(3025 + 2295 + 1960)}{(55 + 45 + 40)}$$

= $$\frac{7280}{140} = 52$$

=> Ans - (C)

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