Question

Find the area of four walls of a room having length, breadth and height as $8$ m, $5$ m and $3$ m respectively. Find the cost of white-washing the walls at the rate of Rs. $15/m^2$.

Answer 1

It is given that length, breadth and height of a room are $8$ m, $5$ m and $3$ m respectively.

Area of four walls of the room is: $2h(l+b)$

$A=2h(l+b)=2\times 3(8+5)=6\times 13=78$ m${}^2$

Area of the ceiling is:

$A=l\times b=8\times 5=40$ m${}^2$

Total area of the four walls and the ceiling of the room is $78+40=118$ m${}^2$

It is given that cost of white washing is Rs.$15$/m${}^2$, therefore,

Total cost of white washing is:

$118\times 15=1770$

Hence, the cost of white washing the walls is Rs.$1770$.