Question:
The dimensions of a room are 12.5 m by 9 m by 7 m. There are 2 doors and 4 windows in the room; each door measures 2.5 m by 1.2 m and each window 1.5 m by 1 m. Find the cost of painting the walls at Rs 3.50 per square meter.
Solution:
Given Length of the room = 12.5 m
Breadth of the room = 9 m
Height of the room = 7 m
Therefore, total surface area of the four walls = 2(l + b) * h
= 2(12.5 + 9) * 7
$=301 \mathrm{~m}^{2}$
Area of 2 doors = 2(2.5 *1.2)
$=6 \mathrm{~m}^{2}$
Area of 4 windows = 4 (1.5*1)
$=6 \mathrm{~m}^{2}$
Area to be painted on 4 walls = 301 - (6 + 6)
= 301 - 12
$=289 \mathrm{~m}^{2}$
Therefore, Cost of painting = 289 * 3.50
= Rs. 1011.5