Question

a verandah 1.25 m wide is constructed all along the outside of a room 5.5 m long and 4m wide.find the cost of cementing the floor of this verandah at the rate of rs 15 per sq m

Answer 1

Area of the room is given by 4 * 5.5 = 22m2

Area of the verandah with room is (5.5 + 1.25 + 1.25) * (4 + 1.25 + 1.25) = 8 * 6.5 = 52

Area of only verandah = 52 - 22 = 30m2

Cost of cementing the floor of the verandah = 15 Rs/m2

Total cost of cementing 30m2 verandah = 30 * 15 = 450 Rs 

Answer 2

Given, Length of room = 5.5m, Width of room = 4m, Width of verandah which is constructed all along outside of room = 1.25m, Cost of cementing of verandha = Rs 15 per m2

Therefore, Length of room with verandah = 5.5m + 1.25m + 1.25m = 8m
Width of room with verandah = 4m + 1.25m + 1.25m = 6.5m

Area of room = Length × width 
= 5.5m × 4m = 22.0 m2

Area of room with verandah = Length × Width
=8m × 6.5m = 52m2

Area of verandah = Area of room with verandah — Area of room 
= 52m2 —22m2 = 30 m2

Cost of cementing of verandah = Area × Rate
Rs 15 x 30m2= Rs 450