Question

a wall has a door length 1.32 M and breadth 0.75 M the length of the wall is 0.5 m and breadth is 4.2 M find the cost of whitewashing the wall is the rate of whitewashing the wall is rupees 20 per square metre

Answer 1

$\mathsf{\huge{Answer}}$

$\bold{Given\:that,}$

Length of the door = 1.32 m.

Breadth of the door = 0.75 m.

Length of the wall = 0.5 m.

Breadth of the wall = 4.2 m.

Rate of whitewashing = $Rs. 20/m^2$

$\bold{To\:find,}$

The rate of whitewashing the wall = ?

Before finding the rate of whitewashing, we have to find the surface area of the door and the wall. Then, we have to subtract the area of wall from door. Because, we don't whitewash the door.

$\bold{We\:know\:that,}$

Surface area of the door = lb

Surface area of the door = $1.32m \times 0.75 m$

Surface area of the door = $0.99 m^2$

$\bold{Therefore,\:area\:of\:door\:is\:0.99m^2.}$

Now, we have to find the surface area of the wall.

$\bold{Surface\:area\:of\:the\:wall} = lb$

Surface area of the wall = $0.5 m \times 4.2m$

Surface area of the wall = $2.1 m^2$

$\bold{Therefore,\:area\:of\:wall\:is\:2.1m^2.}$

Remaining surface that has to be whitewashed = Surface area of the wall - surface area of the door

Remaining surface that has to be whitewashed = $2.1m^2 - 0.99m^2$

Remaining surface that has to be whitewashed = $1.11m^2$

Cost of whitewashing = $Remaining\:surface \times rate$

Cost of whitewashing = $1.11m^2 \times Rs. 20/m^2$

Cost of whitewashing = $Rs. 22.2.$

$\bold{Therefore,\:the\:of\:whitewashing\:is\:Rs.\:22.2.}$