Question

F. A door of length 2 m and breadth Im is fitted in a wall. The length of the
wall is 4.5 m and the breadth is 3.6 m . Find the cost of white
washing the wall, if the rate of white washing the wall is rupees 20 per m2.​

Answer 1

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$\sf\large\bold{\orange{\underline{\blue{ Given :-}}}}$

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• A door of length 2 m and breadth 1 m is fitted in a wall

• Breadth of wall is 3.6 m

• Length of wall is 4.5 m

• Rate of white washing is Rs 20 per m²

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$\sf\large\bold{\orange{\underline{\blue{ To \: Find :-}}}}$

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• Cost of white washing the wall

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$\sf\large\bold{\orange{\underline{\blue{ Solution :-}}}}$

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$\underline{\bold{\texttt{Area of rectangle :}}}$

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➠ L × B ⚊⚊⚊⚊ ⓵

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Where ,

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• L = Length

• B = Breadth

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Clearly the door is in the shape of rectangle

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$\underline{\bold{\texttt{Area of rectangular door :}}}$

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• L = 2

• B = 1

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⟮ Putting the above values in ⓵ ⟯

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➜ L × B

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➜ 2 × 1

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➜ 2 sq. m ⚊⚊⚊⚊ ⓶

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• Hence the area of door is 2 sq. m.

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Also the wall is in the shape of rectangle

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$\underline{\bold{\texttt{Area of rectangular wall including door :}}}$

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• L = 4.5

• B = 3.6

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⟮ Putting the above values in ⓵ ⟯

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➜ L × B

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➜ 4.5 × 3.6

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➜ 16.2 sq. m ⚊⚊⚊⚊ ⓷

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• Hence the area of wall including door is 16.2 sq. m.

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The above area of wall includes the area of door too but white washing need to be done on wall only

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So,

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$\underline{\bold{\texttt{Area of white washing :}}}$

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Area of wall including door - Area of door

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⓷ - ⓶

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➜ 16.2 - 2

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➜ 14.2 sq. m.

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• Hence area of white washing is 14.2 sq. m.

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$\underline{\bold{\texttt{Cost of white washing :}}}$

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Rate of white washing per m² × Area to be white washed in m²

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➜ 20 × 14.2

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➨ Rs 284

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• Hence the cost of white washing the wall is Rs 284