Multiple choice

In a class of 800 students, 56% students are boys. The average weight of all the boys is 75 kg and that of all the girls is 55 kg. Quantity I: What is the average weight of the class? Quantity II: If a boy of 80 kg and a girl of 50 kg is added in the class, then what will be the average weight of the class?

  1. Quantity I > Quantity II

  2. Quantity I < Quantity II

  3. Quantity I ≥ Quantity II

  4. Quantity I ≤ Quantity II

  5. Quantity I = Quantity II or relation can't be established
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A Correct answer
Explanation

Number of boys = 56% of 800 = 448, number of girls = 352. Total weight = 448×75 + 352×55 = 33600 + 19360 = 52960 kg. Average weight (Quantity I) = 52960/800 = 66.2 kg. After adding one boy (80 kg) and one girl (50 kg), total weight = 52960 + 130 = 53090 kg and total students = 802. New average (Quantity II) = 53090/802 ≈ 66.19 kg. Since 66.2 > 66.19, Quantity I is greater.

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