Question

A wall is 4.5 m long and 3 m high. It has two equal windows, each having form and dimension as shown in Fig. Find the cost of painting the wall (leaving window) at the rate of Rs 158 per $m^2$.

Answer 1

Area of wall (including window ) $4.5\times 3=13.5m^2$

Area of window is $80\times 50+\frac{1}{2}\times 80\times 204000c{m}^2+800c{m}^2=4800c{m}^2=0.48m^2$

Area needed to paint $13.5-0.48=13.02m^2$

Cost of painting$=13.02\times 158=2057.16$