Question

A rectangular room of the dimension $8m \times 6m \times 3m$ is to be painted. If it costs Rs.60 per square meter, find the cost of painting the walls of the room.

Answer 1

Hint: In the given question we will try to find the total area of four walls which is also known as Lateral Surface area of room. In lateral surface area we do not include the ceiling of the room, it only includes four walls of a room. After we find the area of the four walls then we will find the cost of painting by multiplying the area with the given value of painting per square meter (we will keep in mind that the unit of the area and cost of painting per square would have the same unit and here it is in ‘meter’).

Complete step-by-step answer: Given,
Dimension of rectangular room;
Length of a room = 8m
Breadth of a room = 6m
Height of a room = 3m
We know that Area of four walls of the room = Lateral surface area of the room
Lateral surface area of the room = 2(length + breadth) × height
= 2 (8 + 6) × 3
= 84 $m^2$
Thus, the area of the four walls is 84 $m^2$.
Given that cost of painting per square meter = Rs. 60
Thus, Cost of painting four walls = Area of four walls of the room × Cost of painting per square meter
$ = 84 \times 60 = 5040$
Hence, the cost of painting the four walls of a rectangular room is Rs 5040.

Note: In this question, remember that Cuboid shaped room includes length, breadth and height of room and we do not include ceiling and floor.