question_answer 8)

A door of length 2 m and breadth 1 m is fitted in a wall. The length of the wall is 4.5 m and the breadth is 3.6 m (figure). Find the cost of white washing the wall, if the rate of white washing the wall is ` 20 per\[{{\text{m}}^{\text{2}}}\].

Answer:

                Length of the door\[=\text{2 m}\] Breadth of the door \[=\text{1 m}\] \[\therefore \]  Area of the door               \[=l\times b=2\times \text{1 }{{\text{m}}^{\text{2}}}\] \[\text{= 2 }{{\text{m}}^{\text{2}}}\] Length of the wall \[=\text{4}.\text{5 m}\] Breadth of the wall \[=\text{3}.\text{6 m}\] \[\therefore \]  Area of the wall \[=l\times b=4.5\times 3.\text{6 }{{\text{m}}^{\text{2}}}\]     \[\text{=16}\text{.20 }{{\text{m}}^{\text{2}}}\] \[\therefore \]  Area of the wall excluding door \[\text{=16}\text{.20 }{{\text{m}}^{\text{2}}}\text{- 2}{{\text{m}}^{\text{2}}}\] \[\text{= 14}\text{.20 }{{\text{m}}^{\text{2}}}\] \[\therefore \] Cost of white washing the wall = ` \[\text{14}\text{.20}\times 20\] = ` 284 Hence, the cost of white washing the wall is ` 284.