A room is `16m` long, `9m` wide and `3m` high. If has two doors, each of dimensions `(2m xx 1.5 m)` and the three windows, each of dimensions `(1.6 m xx 75 cm)`.
Find the cost of distempering the walls of the room from inside at the rate of `Rs 50` per square metre.

Explanation

Area of `4` walls of the room `= [2 (l + b) xx h]` sq units
`=[2(16 + 9) xx 3] m^(2) = 150 m^(2)`
Area of 2 doors `= [2xx (2 xx (3)/(2)] m^(2) = 6m^(2)`
Area of 3 windows `= [3 xx (1.6 xx (75)/(100))]m^(2) = (18)/(5)m^(2) = 3.6 m^(2)`
Area not to be distempered `= (6 + 3.6) m^(2) = 9.6 m^(2)`
Area to be distempered `= (150 - 9.6) m^(2) = 140.4 m^(2)`
Cost of distempering the walls `= Rs (140.4 xx 50) = Rs 7020`