In a class of 65 students there are 39 girls. The average weight of these girls is 60 Kg and average weight of the full class is 64 kgs. What is the average weight of the boys of the class?
Total number of students = 65 and number of girls = 39
=> Number of boys in class = 65 - 39 = 26
Average weight of girls = 60 kg
=> Total weight of girls = $$60 \times 39 = 2340$$ kg
Similarly, total weight of full class = $$64 \times 65 = 4160$$ kg
=> Total weight of boys = 4160 - 2340 = 1820 kg
$$\therefore$$ Average weight of boys = $$\frac{1820}{26} = 70$$ kg
=> Ans - (D)
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