Question

The length of a hall is 18 m and the width 12 m. The sum of the areas of the floor and the flat roof is equal to the sum of the areas of the four walls. Find the height of the wall.

Answer 1

Length of hall (l) = 18 m
and breadth (b) = 12 m
$\therefore$ Area of floor = $l\times b=18\times 12=216m^2$
and area of roof = 216 $m^2$
Total area of floor and roof
= $(216+216)m^2=432m^2$
$\therefore$ Area of four walls = 432 $m^2$
But area of 4 walls = $2(l+b)\times h$
$\therefore$ 2h (l+b) = 432
$\Rightarrow 2h(18+12)=432\Rightarrow 2h\times 30=432$
$\Rightarrow h=\frac{432}{60}$= 7.2 m
$\therefore$ Height of the wall = 7.2 m