Question

9) A class room is 8 m long, 6 m wide and 4.5 m high. It has one door 2.5 m by 1 m and three
windows 1 m by 80 cm. Find :
i) the area of the walls excluding door and windows.
ii) the cost of distempering the walls at the rate of * 4.50 per square m;
ii) the cost of polishing the floor at the rate of 75 paise per square metre.
cm
id.​

Answer 1

Answer:The cost of whitewashing it's four walls at Rs. 4.40 per sq m is 652.08 m².

Step-by-step explanation:

Step 1:

The length of the room, l = 10 m

The breadth of the room, b = 8 m

The height of the room, h = 4.5 m

∴ Area of the walls of the room including the doors and windows = 2h[l+b] = 2*4.5 [10+8] = 162 m² …… (i)

Step 2:

It is given that,

Dimensions of two doors = 2 m x 1.2 m each

So, Area of 2 doors = 2 * [l*b] = 2 * 2 * 1.2 = 4.8 m² ….. (ii)

And,

Dimensions of three windows = 2.5 m x 1.8 m each

So, Area of 3 windows = 2 * [l*b] = 2 * 2.5 * 1.8 = 9 m² ….. (iii)

Step 3:

From (i), (ii) & (iii), we get

Area of 4 walls excluding the doors and windows is,

= [Area of the walls of the room including the doors and windows] – [Area of 2 doors] – [Area of 3 windows]

= 162 – 4.8 – 9

= 148.2 m²

The cost of whitewashing the four walls of the room is given as = Rs 4.40 per sq m

Thus,

The cost of whitewashing the four walls of the room (excluding the doors and windows) is,

= 148.2 * Rs. 4.40

= Rs. 652.08

Step-by-step explanation: