Question

The length of a room is twice its breadth and thrice its height. If the cost of carpeting th floor at Rs 80per sq.metre is Rs 9000,find the cost of plastering its walls and ceiling at rs 35 per sq.metre

Answer 1

Let breadth = x m

Given: Length = 2 (breadth) = 2x

Height= 3 m

Area of door= 4m x 2m =8
{m}^{2}m2 

Now, if the area of four walls excluding door's dimensions, then

Area of four walls-8
{m}^{2}m2 
=100
{m}^{2}m2 
⇒Area of four walls=100+8=108................(i)

Also, Area of four walls=2(length+breadth)×height=2(2x+x)×3=6(3x)=18x..........(ii)

From (i)  & (ii), we get,

18x=108


⇒x=108/18

⇒x=6=breadth

∴length= 2x=12m  and

height = 3m(given)

Thus, Volume = length ×breadth × height= 12×6×3=216
{m}^{2}m2