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Question:
The length, breadth, and height of a room are $5 \mathrm{~m}, 4 \mathrm{~m}$ and $3 \mathrm{~m}$ respectively. Find the cost of whitewashing the walls of the room and the ceiling at the rate of Rs $7.50 \mathrm{~m}$.
Solution:
Total Area to be washed = lb + 2(l + b)h
Where, length (l) = 5 m
breadth (b) = 4 m
height (h) = 3 m
Therefore, the total area to be white washed is = (5*4) + 2*(5 + 4)*3
$=74 \mathrm{~m}^{2}$
Now, The cost of white washing $1 \mathrm{~m}^{2}$ is Rs. $7.50$
Therefore, the cost of white washing $74 \mathrm{~m}^{2}=\left(74^{*} 7.50\right)$
= Rs. 555/-
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