The average weight of the boys in a class is 69.3 kg and that of the girls in the same class is 59.4 kg. If the average weight of all the boys and girls in the class is 63.8 kg, then the percentage of the number of boys in the class is:
Show answer & explanation
Correct answer: D
Explanation
The correct answer is Option 4 i.e. 
| Understanding | Application |
| Tricks |
Let the total number of boys and girls is x and y. So ⇒ 63.8(x + y) = 69.3x + 59.4y ⇒ 63.8x + 63.8y = 69.3x + 59.4y ⇒ 63.8y - 59.4y = 69.3x - 63.8x ⇒ 4.4y = 5.5x ⇒ x/y = 4.4/5.5 |
| Now |
x/y = 4/5 So Percentage = 100/9 × 4 = |