Question 27

There are 40 students in a class. Number of girls is 16 more than number of boys. If the average weight of the girls in the class is 45 kg and the average weight of the overall class (boys + girls) is 47.7 kg, what is the average weight of boys ? (in kg)

Solution

Let the number of boys = $$x$$

=> Number of girls = $$(x + 16)$$

=> Total students = $$x + x + 16 = 40$$

=> $$2x = 40 - 16 = 24$$

=> $$x = \frac{24}{2} = 12$$

=> Number of girls = 12 + 16 = 28

=> Total weight of 28 girls = 28 * 45 = 1260

Total weight of all 40 students = 40 * 47.7 = 1908

=> Total weight of the boys = 1908 - 1260 = 648

$$\therefore$$ Average weight of boys = $$\frac{648}{12} = 54$$ kg

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