A room 5 m long, 4.5 m wide, and 3.6 m high have one door 1.5 m by 2.4 m and two windows, each 1 m by 0.75 m. Find :
(i) the area of its walls, excluding door and windows ;
(ii) the cost of distempering its walls at the rate of Rs.4.50 per m2.
(iii) the cost of painting its roof at the rate of Rs.9 per m2.
Solution
Length of the room = 5 m
The breadth of the room = 4.5 m
Height of the room = 3.6 m
Area of the roof = `"L" xx "B"`
= `5 xx 4.5`m2
= 22.5 m2
Area of four walls = 2[L + B] × H
= 2[5 + 4.5] × 3.6
= 2(9.5) × 3.6
= 19 × 3.6
= 68.4 m2
Area of one door = `1.5 xx 2.4 "m"^2`
= 3.60 m2
= 3.6 m2
Area of one window = `1 xx 0.75`m2
= 0.75 m2
Area of 2 window = `0.75 xx 2`m2
= 1.5 m2
(i) Area of four walls excluding door and windows = 68.4 - (3.6 + 1.5)
= 68.4 - 5.1
= 63.3 m2
(ii) Cost of distempering four walls @ Rs. 4.50 per m2
= 63.3 × 4.50
= Rs. 284.85
(iii) Cost of painting the roof @ Rs.9 per m2
= 22.5 × 9
= Rs. 202.50
