Question

Mohan wanted to paint the walls and ceiling of a hall. The dimensions of the hall is 20mx 15mx 6m. Find the area of surface to be painted and the cost of painting it at ₹ 78 per
sq. m.​

Answer 1

GIVEN :

• The dimensions provided of the Hall = 20m, 15m and 6m respectively.

• The cost of the painting the walls and ceilings = ₹ 78per metre Sq.

TO FIND :

• The cost of painting walls and ceilings at ₹78 per metre Sq. = ?

STEP - BY - STEP EXPLAINATION :

So, as per the provided question we have the provided information and now we will have to find the cost of painting walls and ceilings, let's being :

Now, let us consider :

➠ Length = 20m

➠ Breadth = 15m

➠ Height = 6m

Now, we will have to calculate the cost of painting ceilings and walls at ₹78 per metre Sq. = ?

Let us assume the value to be taken out = x

(Applying here the formula) :

• 2 (l+b) h

[ Hidden sign shows the sign of Multiplication]

[ substituting the values as per the formula]

⟶ 2×(l+b) ×h

⟶ 2 × (20+15) × 6 m²

⟶ (2 × 6) × (20+15) m² [ simplifying ]

⟶ 12 × 35 m²

⟶ 420 m² [ Area of the walls ]

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Now, here we will find the area for painting the ceiling :

( Applying here the Formula ) :

• Area (Rectangle) = Length × Breadth

[ Substituting the values as per Formula]

⟶ Area = Length × Breadth

⟶ Area = 20 × 15 m²

⟶ Area = 300m²

━━━━━━━━━━━━━━━━━━━━━━━━━

So, now we will have to find the the area of the surface that is to be painted :

⟶ Area gained (ceilings) + Area (Walls)

[ Substituting the values as per formula ]

⟶ 300m² + 420m²

⟶ 720m²

Hence, now we will find the the cost of painting at ₹78 per metre Sq.

⟶ Area (obtained to be painted.) × cost price

[ Substituting the values as per formula ] :

⟶ 720 × ₹78

⟶ ₹5,6160

Therefore, the cost price of painting the walls and ceilings at ₹78 per metre Sq. = ₹ 5,6160

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★ Some important formula, that is to be applied for solving these kinds of sum :

• Area of the rectangle = L × B

• Perimeter of the rectangle = 2 (l+b)

• Area of the square = Side × Side

• Perimeter of the square = 4 × Side

• Area of the circle = πr²

• Perimeter of the triangle = A + B + C

• Area of the triangle = 1/2 × B × H