Question

The dimensions of a room are 14 m × 10 m × 6.5 m. There are two doors and 4 windows in the room. Each door measures 2.5 m × 1.2 m and each window measures 1.5 × 1 m. Find the cost of painting the four walls of the room at Rs 38 per m².

Answer 1

The room has four walls to be painted.

$$\begin{gathered} \mathrm{Area}\mathrm{of}\mathrm{these}\mathrm{walls}=2(l\times h)+2(b\times h) \\ =\left(2\times 14\times 6.5\right)+\left(2\times 10\times 6.5\right) \\ =312{\mathrm{m}}^2 \end{gathered}$$

Now,
Area of the two doors = $\left(2\times 2.5\times 1.2\right)=6{\mathrm{m}}^2$

Area of the four windows = $\left(4\times 1.5\times 1\right)=6{\mathrm{m}}^2$

The walls have to be painted; the doors and windows are not to be painted.

∴ Total area to be painted$=312-\left(6+6\right)=300{\mathrm{m}}^2$
Cost for painting 1 m² = Rs 38
Cost for painting 300 m² = $300\times 38=\mathrm{Rs}11400$