1.

The ratio of the number of boys and girls in a class is 9 ∶ 7. The average weight of all the boys and girls is 54.25 kg. If the average weight of the girls is 52 kg, then what is the average weight (in kg) of the boys?1. 56.52. 57.53. 574. 56

Answer» Correct Answer - Option 4 : 56

Given :

The ratio of boys and girls in class = 9 ∶ 7

the average weight of all boys and girls = 54.25 kg

the average weight of all girls = 52 kg

Concept used :

 \({Average\ weight}= {Total \ weight \over Total\ no.\ of\ people}\)

Calculation :

Let the no. of boys and girls be 9 units and 7 units

According to the question,

Total weight of all the boys and girls = 16 (units) × 54.25 kg

⇒ 868 kg

Also, the Total weight of all the girls = 7 (units) × 52 kg

⇒ 364 kg

⇒ Total weight of all the boys = Total weight of all the boys and girls - Total weight of all the girls

⇒ Total weight of all the boys = 868 - 364

⇒ Total weight of all the boys = 504 kg

⇒ The average weight of all the boys = Total weight of all the boys / Total number of boys

⇒ The average weight of all the boys = 504/9

⇒ 56

∴ The average weight of the boys is 56 kg

 



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