Question

9. The length, breadth and height of a room are 9m, 8m and 7 m respectively. Find the

cost of plastering the four walls and ceiling of the room at the rate of ₹ 7 per sq m.​

Answer 1

volume of cuboid = l × b× h

Answer 2

Given, length of the room (l) = 4.5 m

Breadth of the room (b) = 3m

Height of the room (h) = 350 cm = 3.5 m

And the cost of plastering = Rs. 8perm

2

Therefore, the area of the walls = 2h(l+b)

= 2×3.5×(4.5+3) = 7×(7.5) = 52.2 m

2

Area of the ceiling = lb = 4.5×3 = 13.5m

2

Area of the room = 52.5+13.5 = 66m

2

Hence, the cost of plastering = 66×8 = Rs 528