Question

The dimensions of a room are $(9m\times 8m\times 6.5m)$. It has one door of dimensions $(2m\times 1.5m)$ and two windows, each of dimensions $(1.5m\times 1m)$. Find the cost of whitewashing the walls at $Rs.25$ per square meter.

Answer 1

Total surface area of the room$=2(lh+lb+hb)m^2$

$=2[9\times 6.5+9\times 8+8\times 6.5]m^2=365m^2$

Area of the door $=l\times b=2\times 1.5=3m^2$

Area of the windows$=l\times b=1.5\times 1=1.5m^2$

$\therefore$ Surface area of walls$=$TSA of room $-$Area of door$-$Area of windows

$=365-3-1.5=360.5m^2$

Cost of whitewashing per square meter$=$Rs. $6.40$

$\therefore$ Cost of whitewashing the walls$=$Rs. $6.40\times 360.5$

$=$Rs. $2307.2$.