Question

The length, breadth, and height of a room are $5\mathrm{m},4\mathrm{m}\mathrm{and}3\mathrm{m}$respectively. Find the cost of whitewashing the walls of the room and ceiling at the rate of $\mathrm{Rs}.750\mathrm{per}{\mathrm{m}}^2$.

Answer 1

Calculate the cost of whitewashing.

The length $\left(l\right)$, breadth $\left(b\right)$, and height$\left(h\right)$ of a room are $5\mathrm{m},4\mathrm{m}\mathrm{and}3\mathrm{m}$respectively.

$$\begin{gathered} \mathrm{Area}\mathrm{of}\mathrm{whitewashing}=\mathrm{Area}\mathrm{of}\mathrm{walls}+\mathrm{Area}\mathrm{of}\mathrm{ceiling} \\ \Rightarrow =2lh+2bh+lb \\ \Rightarrow =\left(2\times 5\times 3\right)+\left(2\times 4\times 3\right)+\left(5\times 4\right) \\ \Rightarrow =30+24+20 \\ \Rightarrow =74{\mathrm{m}}^2 \end{gathered}$$

Since the rate of whitewashing is $\mathrm{Rs}.750\mathrm{per}{\mathrm{m}}^2$.

Thus, the total cost of whitewashing$=74\times 750=\mathrm{Rs}.55500$

Hence, the total cost of whitewashing is $\mathrm{Rs}.55500$.