Question

The floor of a rectangular hall has a perimeter 250 m. If the cost of panting the four walls at the rate of Rs.10 per m² is Rs.15000, find the height of the hall.

[Hint: Area of the four walls = Lateral surface area.]

Answer 1

Let length, breadth, and height of the rectangular hall be l m, b m, and h m respectively.

Area of four walls = 2lh + 2bh

= 2(l + b) h

Perimeter of the floor of hall = 2(l + b)

= 250 m

∴ Area of four walls = 2(l + b) h = 250h m²

Cost of painting per m² area = Rs 10

Cost of painting 250h m² area = Rs (250h × 10) = Rs 2500h

However, it is given that the cost of paining the walls is Rs 15000.

∴ 15000 = 2500h

h = 6

Therefore, the height of the hall is 6 m.