Question

the length of a room is twice its breadth and thrice its height.if the cost of carpeting the floor at rs.80 per sq.metre is rs.9000,find the cost of plastering its wall and ceiling at rs.35 per.sq​

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