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

Let, the lenght of hall = l m, breadth = b m and height = h m
Permeter of floor = 2(l + b)
According of question, 2(l + b) = 250 m …(1)
Area of four walls of hall = 2(l + b) h
So, the cost of painting the four walls at the rate of Rs 10 per m² = 2(l + b) h × Rs 10
= 250h × Rs 10 [∵ From equation (1)]
= Rs 2500h
According to question, Rs 2500h = 15000
⇒ h = 15000/2500 = 6 m
Hence, the height of the hall is 6 m.