The average weight of 100 students in a class is 46 kg. The average weights of boys and girls are 50 kg and 40 kg respectively. What is the difference between the number of boys and girls?
This questions was previously asked in
EPFO AO EO 2021
Explanation:
Let's break down the problem:
- Let the number of boys be B and girls be G.
- Total students = 100, so: B + G = 100.
- Total weight = 100 × 46 = 4600 kg.
- Weight of boys = B × 50 kg.
- Weight of girls = G × 40 kg.
- So, B × 50 + G × 40 = 4600.
Solving equations:
1. B + G = 100
2. 50B + 40G = 4600
From (1): G = 100 - B
Substitute into (2):
50B + 40(100 - B) = 4600
50B + 4000 - 40B = 4600
10B = 600
B = 60, G = 40
Difference = |60 - 40| = 20
Options:
- Option 1: 30 (Not correct)
- Option 2: 25 (Not correct)
- Option 3: 20 (Correct)
- Option 4: 10 (Not correct)
Option 3: 20 is the correct answer.
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By: MIRZA SADDAM HUSSAIN