Question

The length, breadth and height of a room are 5 m, 4 m and 3 m respectively. Find the
cost of white washing the walls of the room and the ceiling at the rate of
Rs 7.50 per m2​

Answer 1

Step-by-step explanation:

Given :

• The length, breadth and height of a room are 5 m, 4 m and 3 m respectively.

To Find :

• Find the cost of white washing the walls of the room and the ceiling at the rate of Rs 7.50 per m²

Solution :

Concept :

• This lateral surface area can be calculated by multiplying the perimeter of the base by the height of the prism.

• For a right circular cylinder of radius r and height h, the lateral area is the area of the side surface of the cylinder: A = 2πrh.

Lateral surface area = L × B

= 2h (L + B) + L × B

substitute all values :

$\sf \: : \implies \: \: \: \: \: \: \: \: \: \: \: \: \: 2 \times 3(5 + 4) + 5 \times 4 \: \: \: \\ \\ \\ \sf \: : \implies \: \: \: \: \: \: \: \: \: \: \: \: \:2 \times 3(9) + 20 \\ \\ \\ \sf \: : \implies \: \: \: \: \: \: \: \: \: \: \: \: \:2 \times 27 + 20 \\ \\ \\ \sf \: : \implies \: \: \: \: \: \: \: \: \: \: \: \: \:54 + 20 \\ \\ \\ \sf \: : \implies \: \: \: \: \: \: \: \: \: \: \: \: \:74$

According to the Question :

• Cost of white washed 1m = Rs. 7.50

$\sf \: : \implies \: \: \: \: \: \: \: \: \: \: \: \: \:74 \times \frac{750}{100} \\ \\ \\ \sf \: : \implies \: \: \: \: \: \: \: \: \: \: \: \: \:555$