Question

in a school with 600 students the average age of the boys is 12 years andthat of the girls is 11 years if the average age of the school is 11 years and 9 months then the number of girls in the school is

Answer 1

Given :

To students in school , S = 600 .

Average height of boy , B = 12 .

Average height of girl , G = 11 .

Average age of student in school , $A=11\dfrac{9}{12}=\dfrac{47}{4}=11.75$ .

To Find :

The number of girls in the school .

Solution :

Let , number of girls are x .

Average age is given by :

$A=\dfrac{\text{Sum of age}}{\text{Total Students}}$

$11.75=\dfrac{11x+12(600-x)}{600}\\\\11x+7200-12x=7050\\\\x=7200-7050\\\\x=150$

Therefore , number of girls in the school is 150 .

Hence , this is the required solution .