Question

A class is 7 m long, 6 m board and 3.5 m high. Doors and windows occupy an area of 17 $m^2$. What is the cost of white-washing the walls at the rate of Rs. 1.50 per $m^2$.

Answer 1

Length of room (l) = 7 m
Breadth (b) = 6 m
and height (h) = 3.5 m
$\therefore$ Area of four walls = $2(l+b)\times h$
= $2(7+6)\times 3.5m^2=2\times 13\times 3.5=91m^2$
Area of doors and windows = 17 $m^2$
\therefore Remaining area of walls = 91 -17 = 74 $m^2$
Rate of whitewashing = Rs. 1.50 per $m^2$
$\therefore$ Total cost = 74 $\times$ Rs. 1.50 = Rs. 111