NCHMCT JEE 2010 Question Paper with solutions for online practice

Question : 18 of 200

Marks: +1, -0

The average age of a class is 15.8 yr. The average age of the boys in the class is 16.4 yr while that of the girls is 15.4 yr. What is the ratio of boys to girls in the class?

1 : 2
3 : 4
3 : 5
None of these

Validate

Solution:

Let there are x boys and y girls.
Average age of class = 15.8 yr
Total age of class = 15.8 (x + y) yr
Average age of boys = 16.4 yr
Total age of boys = 16.4x yr
Average age of girls = 15.4 yr
Total age of girls = 15.4y yr
Hence, 15.8(x + y) = 16.4x + 15.4y
⇒ 15.8y – 15.4y = 16.4x – 15.8x
⇒ 0.4y = 0.6x
⇒

x/y

2/3

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