Average age of students of a class is 15.8 years. average age of boys in class is 16.4, years and th

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The average age of students of a class is $15.8$ $years.$ The average age of boys in the class is $16.4\, years$ and that of the girls is $15.4 \,years.$ The ratio of the number of boys to the number of girls in the class is

A

$1: 2$

B

$2: 3$

C

$3: 4$

D

$3: 5$

Solution

Average age of boys $=16.4$ $years$

Average age of girls $=15.4$ $years$

Let $m$ be number of boys and $n$ be number of girls.

$\frac{m \times 16.4+n(15.4)}{m+n}=15.8$

$16.4 m+15.4 n=15.8 m+15.8 n$

$0.6 m=0.4 n$

$\frac{m}{n}=\frac{0.4}{0.6}=\frac{2}{3}$

Standard 13

Quantitative Aptitude

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