Question

The length of a room is three times its breadth and its volume is 240 cubic metre. The cost of plastering its four walls at Rs.50 per metre square is Rs.8000,find the height of the room?

Answer 1

Answer:

Step-by-step explanation:

Let breadth =x

then length=3x

Let height=h

volume=x*3x*h=240

3x²h=240

x²h=80--------------(1)

Now The cost of plastering its four walls  = Rs.8000

rate=Rs 50/m²

so area=8000/50=800/5=160 m²

Now area of 2 walls in length =2*length*height=2*3x*h=6xh

Area of 2 walls in breadth =2*breadth*height=2*x*h=2xh

6xh+2xh=160

8xh=160

xh=20-----(2)

From (1)

x²h=80

x*xh=80

x*20=80

x=80/20=4 m

From(2)

xh=20

4h=20

h=20/4=5 m

So Height =5 m, breadth = 4 m ,Length=3x=12 m