Question

the length of a classroom is twice its height and teh breadth is 1 1/2 times its height. The cost of white washing the walls at teh rate of 1.60 per m2 is rs i79.20. Find the cost of tiling the floor at the rate of Rs 6.75 per m2

Answer 1

Given:

Let the height of class room be =h

Then length of class room (l)= 2h

And Breadth of class room (b) = (3/2)h

Rate for painting walls = Rs. 1.60/m²

Cost of painting walls = Rs. 179.20

Rate of tiling the floor = Rs. 6.75/m²

To find:

We have to find the cost of tiling the floor

Solution:

To knoe the cisy of tiling we need get the area of the floor= l×b

Here l and b values are in terms of h

So first we need to find the value of h by following way

Cost of painting walls = Rate of painting walls×Area of 4 walls

                         179.20= Rate of painting walls×[ 2lh + 2bh ]

                                    = $(1.60)$ × $[2(2h)(h)+2(\frac{3}{2}h)(h) ]$

                         179.20= $(1.60)$ ×$[4h^{2}+3h^{2}]$

                              $7h^{2}$ = $\frac{179.20}{1.60}$

                              $7h^{2}$ =$112$

                               $h^{2}=\frac{112}{7}$

                                $h$ = $\frac{4\sqrt{7} }{\sqrt{7} }$

                                $h = 4$

Now  $h = 4m$

$l=2h=2(4)=8m$

$b=\frac{3}{2}h=\frac{3}{2}(4)=6m$

Now cost of tiling the floor = Rate of tiling×(Area of floor)

                                            = $6.75$ × $(lb)$

                                            = $6.75$ × $(8$ × $6)$

                                            = $6.75$ × $(48)$

                                            = $324$

∴Cost of tiling the floor = Rs. 324