question_answer

The walls and ceiling of a room are to be plastered. The length, breadth and height of the room are 4.5 m, 3 m, and 350 cm respectively. Find the cost of plastering at the rate of Rs. 8 per\[{{m}^{2}}\].

Answer:

Here, l = 4.5 m, b = 3 m, h = 350 cm = 3.5 m.

Total surface area of room (cuboid) \[=2\left[ lb+bh+hl \right]\]

\[=2\left[ 4.5\times 3+3\times 3.5\times +3.5\times 4.5 \right]\]

\[=2\left[ 13.5+10.5+15.75 \right]\]

\[=2\left[ 39.75 \right]\]

\[\,=79.5\text{ }{{m}^{2}}\]

Required area for plastering = 79.5 - Area of base (surface)

= 79.5 - 13.5

= 66 \[{{m}^{2}}\]

Cost of plastering \[=66\times 8\]

= Rs. 528