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In a primary school the average weight of male students is…

September 6, 2022 by Prabhat

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In a primary school the average weight of male students is 65.9 kg and the average weight of female students is 57 kg. If the average weight of all the students ( both male and female ) is 60.3 kg and the number of male students in the school is 66, what is the number of female students in the school?

A. 162
B. 168
C. 180
D. 112

Answer: Option D

Here is complete explanation of In a primary school the average weight of male students is….

Solution(By ExamCraze Team)

Let the number of female students be x
Let weight of female students = 57x
Number of male students = 66
Total weights of male students = 65.9 × 66
Average weight of all the students = 60.3 kg
Total weights of all the students = 60.3 (66 + x)
According to given information,
Then,
⇒ 60.3 (66 + x) = 66 × 65.9 + 57x
⇒ 60.3 × 66 + 60.3x = 66 × 65.9 + 57x
⇒ 60.3x - 57x = 66 (65.9 - 60.3)
⇒ 3.3x = 66 × 5.6
∴ x = $$frac{66 × 5.6}{3.3}$$
⇒ x = 2 × 56
⇒ x = 112