Question 78

The mean of marks secured by 60 students in division A of class X is 66, 45 students of division B is 62 and that of 75 students of division C is 60. Find the mean of marks of the students of three divisions of Class X.

Solution

Total marks secured by 60 students in division A = 60 $$\times$$ 66 = 3960

Total marks secured by 45 students in division B = 45 $$\times$$ 62 = 2790

Total marks secured by 75 students in division C = 75 $$\times$$ 60 = 4500

=> Mean of marks of the students of three divisions of Class X = $$\frac{(3960 + 2790 + 4500)}{(60 + 45 + 75)}$$

= $$\frac{11250}{180} = 62.5$$

=> Ans - (B)

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