Question

the avearage height of girls 154cm and that of boys is 4cm more than the average height of all the students in the class . if the number of girls is 20% less than boys. then what is the average height of boys

Answer 1

Given that average height of the girls = 154 cm

Let average height of the boys = x cm

Then average height of all the students in the class is given by average of 154 and x whichis

$\frac{(154+x)}{2}$

Given that avearage height of boys is 4cm more than the average height of all the students in the class. So we can write equation:

$x-\frac{(154+x)}{2}=4$

$2x-2*\frac{(154+x)}{2}=2*4$

$2x-(154+x)=8$

$2x-154-x=8$

$x-154=8$

$x=154+8$

x=162

Hence final answer is 162 cm.