Question

The floor of a rectangular hall has a perimeter 250 m. If the cost of painting the four
walls at the rate of 10 per m'is 15000, find the height of the hall.
Hint: Area of the four walls = Lateral surface area.]
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Answer 1

Answer:

Given:

Perimeter=250m

⇒Area of 4 walls =2lh+2bh

=2(b+l)h

⇒Perimeter of floor of wall =2l+2b

⇒2(l+b)=250 m

∴ Area of 4 walls =2(l+b)h

=250h m

2

⇒Cost of painting per m

2

area = Rs. 10

⇒Cost of painting 250h m

2

area = Rs(250h×10)

= Rs.2500h

⇒Painting cost of walls = Rs. 15000

⇒2500h=15000

⇒h=

2500

15000

⇒h=6m