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

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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?

1. A. 162
2. B. 168
3. C. 180
4. D. 112

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