Answer:

Step-by-step explanation:

Length, breadth and height of a room are 5 m, 4 m and 3 m.

Area of four walls of the room = 2h(l + b)

= 2 x 3 (5 + 4)  

= 6(9)

= 54 sq m

Area of the ceiling = l x b

= 5 x 4

= 20 sq cm.

Total area of the four walls and the ceiling of the room

= 54 + 20

= 74 sq cm

Cost of white washing = Rs 7.50 per sq m