Question 79

The mean of marks secured by 45 students in division A of class X is 69, 65 students of division B is 65 and that of 50 students of division C is 63. Find the mean of marks of the students of three divisions of Class X.

Solution

Total marks secured by 45 students in division A = 45 $$\times$$ 69 = 3105

Total marks secured by 65 students in division B = 65 $$\times$$ 65 = 4225

Total marks secured by 50 students in division C = 50 $$\times$$ 63 = 3150

=> Mean of marks of the students of three divisions of Class X = $$\frac{(3105 + 4225 + 3150)}{(45 + 65 + 50)}$$

= $$\frac{10480}{160} = 65.5$$

=> Ans - (A)

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