# Q. 8.     A door of length $2\; m$ and breadth $1\; m$ is fitted in a wall. The length of the wall is $4.5\; m$ and the breadth is$3.6\; m$ (Fig11.6). Find the cost of white washing the wall, if the rate of white washing the wall is $Rs.20\; per\; m^{2}$

R Riya

It is given that the length of door is $2\; m$ and breadth is  $1\; m$ and the length of the wall is $4.5\; m$ and the breadth is$3.6\; m$

Now, we know that

Area of rectangle is $= length \times breath$

Thus, the area of the wall is

$\Rightarrow 4.5 \times 3.6 =16.2 \ m^2$

And

Area of the door is

$\Rightarrow 2 \times 1 =2 \ m^2$

Now, Area to be painted = Area of wall - Area of door = 16.2 - 2 = 14.2 $\ m^2$

Now, the cost of whitewashing the wall, at the rate of $Rs.20\; per\; m^{2}$ is

$\Rightarrow 14.2 \times 20 = 284 \ Rs$

Therefore, the cost of whitewashing the wall, at the rate of $Rs.20\; per\; m^{2}$ is Rs 284

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