Question

The cost of preparing the walls of a room 12 m long at the rate of Rs 1.35 per square metre is Rs 340.20 and the cost of matting the floor at 85 poise per square metre is Rs 91.80. Find the height of the room.

Answer 1

Length of the room (l) = 12 m
Rate of matting the floor = 85 paise per $m^2$
Total cost of matting = Rs. 91.80
$\therefore$ Area of floor = $\frac{91.80}{0.85}$ = $\frac{9180}{85}{m}^2=108m^2$
$\therefore$ Breadth (b) = $\frac{Area}{Length}=\frac{108}{12}$= 9 m.
Now rate of preparing the walls = Rs. 1.35 per $m^2$
Total cost = Rs. 340.20
$\therefore$ Area of walls = $\frac{340.20}{1.35}=\frac{34020}{135}{m}^2$
=252 $m^2$
But area of 4 walls = $2(l+b)\times h$
$\therefore 2(l+b)\times h=252$
$\Rightarrow$ 2h (12+9)= 252
$2h\times 21=252$
h= $\frac{252}{42}$ =6
$\therefore$ Height of the room = 6 m