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.

Answer 1

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