In a class of 50 students there are 27 boys. The average weight of these boys is 72 Kg and average weight of the full class is 55.44 kgs. What is the average weight (in kgs) of the girls of the class?
A) 42 B) 48 C) 30 D) 36
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- Total number of students = 50
- Number of boys = 27
→ Then, number of girls = 50 - 27 = 23
Average weight of boys = 72 kg
We know,
◙ Average weight of boys = Total weight of all the boys/Number of boys
Let the total weight of all the boys be x.
⇒72 = x/27
⇒x = 72 × 27
⇒x = 1944 kg
Average weight of the class = 55.44 kg.
Let the total weight of all the girls be y.
Again,
→ Average weight of the class = (x + y)/2
⇒55.44 = (1944 + y)/50
⇒1944 + y = 55.44 × 50
⇒1944 + y = 2772
⇒y = 2772 - 1944
⇒y = 828 kg
→ Average weight of all the girls = 828/23
⇒Average weight of all the girls = 36 kg
Therefore, the answer is D) 36 kg.
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