Question 55

The average weight of all the students in a class was 45.5 kg. Later on 5 students weighing 44.6 kg 43.4 kg, 44 kg, 45.5 kg and 43.5 kg leave the class. As a result, the average weight of the remaining students increases by 500g. What was the number of students in the class, initially?

Solution

Let the number of students initially be $$x$$

=> Total weight of the class = $$45.5x$$ kg

Sum of weights of students who left = $$(44.6+43.4+44+45.5+43.5)=221$$ kg

Thus, new average = $$\frac{45.5x-221}{x-5}=46$$

=> $$45.5x-221=46x-230$$

=> $$0.5x=9$$

=> $$x=\frac{9}{0.5}=18$$

$$\therefore$$ There were 18 students initially.

=> Ans - (A)

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