Question

$\text{The dimensions of a room are}(9m\times 8m\times 6.5m).\text{It has one door of dimensions}(2m\times 1.5m)\text{and two windows, each of dimensions}(1.5m\times 1m).\text{Find the cost of whitewashing the walls at Rs25 per square metre.}$

Answer 1

Length of room = 9 m
Breadth of room = 8 m
Height of room = 6.5 m
Total Surface Area of room = 2(lb + bh + hl) – lb [Floor is excluded]
= 2[9x8 + 8x6.5 + 6.5x9] – 9x8
= 293 sq m
Area of one door = 2 x 1.5 = 3 sq m
Area of 2 windows = 2 x 1.5 x 1 = 3 sq m
Area of walls to be white washed = 293 – 6 = 287 sq m
Cost of white washing the walls at Rs 25 per sq m = Rs 25 x 287
= Rs 7175