4. A room 5 m long, 4.5 m wide and 3-6 m high
has one door 1.5 m by 2.4 m and two
windows, each 1 m by 0.75 m. Find : i ) the area of four walls excluding doors and windows.
ii) the cost of distempering it's wall at rate of rupees 4.50 per metre square .
iii) the cost of painting its roof at the rate of rupees 9:00 per metre square .
Answers
dimensions of room
l = 5m. b = 4.5m. h = 3.6m
Area of 4 walls = Lateral Surface Area of the room
= 2(l+b)h
= 2(5+4.5)3.6
= 2(9.5)3.6
= 68.5m²
length of the door = 1.5m
breadth of the door = 2.4m
area = l×b = 1.5×2.4 = 3.6m²
length of the window = 1m
breadth of the window = 0.75m
Area = l×b = 1×0.75 = 0.75m²
Area covered by 2 windows = 2×0.75 = 1.5m²
Total Area covered by one door and 2 windows
= 3.6m²+1.5m² = 5.1m²
i) area of walls excluding doors and windows
= 68.5m² - (3.6m²+1.5m²)
= 68.5m² - (5.1m²)
= 63.4m²
ii) cost of distemperring the walls = Rs.4.5/m²
cost of distemperring the walls of area 63.4m²
= 63.4m²×4.5 = Rs. 285.3
iii) Area of the roof = l×b = 5×4.5 = 22.5m²
cost of painting = Rs. 9/m²
cost of painting the area of roof = 22.5×9 =
Rs.202.5
I hope this answer helps you.