Question

The dimension of a room is 7m × 5m × 10m.Find the cost of whitewashing the walls of the room, excluding the floor at the rate of Rs 1.5 per sq m.
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Answer 1

Your answer:-

Total surface area of the room=2(lh+lb+hb)m2

=2[9×6.5+9×8+8×6.5]m2=365m2

Area of the door =l×b=2×1.5=3m2

Area of the windows=l×b=1.5×1=1.5m2

∴ Surface area of walls=TSA of room −Area of door−Area of windows

=365−3−1.5=360.5m2

Cost of whitewashing per square meter=Rs. 6.40

∴ Cost of whitewashing the walls=Rs. 6.40×360.5

=Rs. 2307.2.

Refer to attachment for more help !!

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