Solution —
Length (l) of room = 5m
Breadth (b) of room = 4m
Height (h) of room = 3m
According to the question four walls and the ceiling of the room are to be white washed.
Total area to be white washed = Area of walls + Area of ceiling of room
= 2lh+2bh+lb
= [2×5×3+2×4×3+5×4]
= (30+24+20)
= 74
Area = 74 m2
Also,
Cost of white wash per m2 area = Rs.7.50 (Given in question )
Cost of white washing 74 m2 area = Rs. (74×7.50)
= Rs. 555