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The average weight of a class of 15 boys and 10 girls is 38.4 kg. If the average weight of the boys is 40 kg, then what is the average weight of the girls?

A) 36.5 kg
B) 35 kg
C) 36 kg
D) 35.6 kg

Correct Answer:



C) 36 kg

Description for Correct answer:

Given that, number of boys \( \Large n_{1} \) = 15

Number of girls \( \Large n_{2} \) = 10

Average weight of boys and girls = 38.4 kg

Average of boys = 40 kg

Let average of girls be \( \Large a_{2} \)

By formula, average = \( \Large \frac{n_{1}a_{1} + n_{2}a_{2}}{n_{1} + n_{2}} \)

=> \( \Large 38.4 = \frac{15 \left(40\right)+ 10 \times a_{2}}{15+10} \)

=> \( \Large 38.4 \times 25 = 600 + 10a_{2} \)

=> \( \Large a_{2} = \frac{900-600}{10} = \frac{360}{10} = 36 kg \)

Part of solved Average questions and answers : >> Aptitude >> Average

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