Question
The floor of a rectangular hall has a perimeter of 250 m. If the cost of painting the four walls at the rate of 10 per m2 is Rs 15000. Find the height of the hall.
Solution
Let the height of the hall be h metres. Then,
Area of the four wall = Perimeter of the floor × height = (250 × h) m2
= 250 h m2
⇒ Cost of painting of 1 square metre = Rs 10
⇒ Cost of painting of the four walls = Rs (250 h × 10)
= Rs 2500 h
⇒ Cost of painting of four walls is Rs 15000. [given]
∴ 2500 h = 15000
⇒ 
Here, the height of the hall is 6 m.
