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Question
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.
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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
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