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There are 120 students in a class. The number of boys is 40% more than the number of girls in the class. The average age of boys in the class is 24 years and the average age of the whole class is 30 years. Then, what is the average age of girls in the class?

There are 120 students in a class. The number of boys is 40% more than the number of girls in the class. The average age of boys in the class is 24 years and the average age of the whole class is 30 years. Then, what is the average age of girls in the class? Correct Answer 38.4 years

Given:

Total students = 120

The number of boys = 140% of the number of girls

The average age of boys = 24 years

The average age of whole class = 30 years

Calculation:

The ratio of boys and girls = 140 : 100 = 7 : 5

Suppose, the average age of girls is K years.

Sum of the age of whole class = 30 × 12 = 360

According to question -

⇒ (7 × 24) + (5× K) = 360

⇒ 168 + 5K = 360

⇒ 5K = 360 - 168

⇒ K = 192 / 5

⇒ K = 38.4 years

∴ The average age of girls is 38.4 years.

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