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 m^{2}.

(iii) the cost of painting its roof at the rate of Rs.9 per m^{2}.

#### 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`m^{2}

= 22.5 m^{2}

Area of four walls = 2[L + B] × H

= 2[5 + 4.5] × 3.6

= 2(9.5) × 3.6

= 19 × 3.6

= 68.4 m^{2}

Area of one door = `1.5 xx 2.4 "m"^2`

= 3.60 m^{2}

= 3.6 m^{2}

Area of one window = `1 xx 0.75`m^{2}

= 0.75 m^{2}

Area of 2 window = `0.75 xx 2`m^{2}

= 1.5 m^{2}

(i) Area of four walls excluding door and windows = 68.4 - (3.6 + 1.5)

= 68.4 - 5.1

= 63.3 m^{2}

(ii) Cost of distempering four walls @ Rs. 4.50 per m^{2}

= 63.3 × 4.50

= Rs. 284.85

(iii) Cost of painting the roof @ Rs.9 per m^{2}

= 22.5 × 9

= Rs. 202.50