Question

The floor of a cuboidal hall has perimeter equal to 250 m and height 6 m. Find the cost of painting its four walls (including doors etc) at the rate of Rs.8 per square metre.

Answer 1

Given that, the perimeter of floor of a rectangular hall is $250m$.

Also, the height of walls, $h=6m$.

To find out: Cost of painting the four walls (including doors) at the rate of $Rs.8per{m}^2$.

Two walls of the hall will have dimensions $l\times h$ and the rest two will have $b\times h$.

Hence, the total area of four walls $=2(l\times h)+2(b\times h)=2h(l+b)$.

Given that the perimeter is $250m$.

$\therefore 2(l+b)=250$.

Hence, area of four walls $=h\times 2(l+b)=6\times 250=1500m^2$

Now, cost of painting $1m^2$ area is $Rs.8$.

$\therefore$ Cost of painting $1500m^2=8\times 1500=Rs.12000$.

Hence, the cost of painting the four walls of the hall is $Rs.12000$.