Question

Rahul is constructing his house. He wants to make a Hall of dimension 20m × 15m, such that it has a border of black granite 0.5 m wide on all four sides and a black granite circle in the middle of radius 1.4 m. Calculate the cost of granite used at Rs. 1200 per square metre.​

Answer 1

Answer:

₹48,192

Step-by-step explanation:

Dimensions of the hall is 20 m × 15 m.

Then, area of the hall = Length × Width = 20 × 15 = 300 m²

Now, as the hall has a border of granite 0.5 m wide on all sides.

The dimensions of the hall with granite border is (20-2×0.5) = (20-1) = 19 m and (15-2×0.5) = (15-1) = 14 m.

Thus, the total area of the hall with the border = Length × Width = 19 × 14 = 266 m²

Since, the granite is used on the border.

So, the area of the granite used = 300 - 266 = 34 m².

Also, the granite is used to make a circle of radius 1.4 m.

Then, area of the circle = πr²

i.e. area of the circle =π(1.4)²

area of the circle = 22/7(1.4)²

Area of the circle = 6.16 m²

Thus, the total area of the granite = 34 + 6.16 = 40.16 m²

Since, the cost of granite per square meter = ₹1200.

So, the cost of 40.16 m² = 1200 × 40.16 = ₹48,192.

Hence, the total cost of the granite is ₹48,192.

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Answer 2

Step-by-step explanation:

Perimeter of hall = 2(20+15) = 2(35)=

70m

Granite used on four sides= 70×0.5 = 35 sq. m

Circumference of circle = 2πr = 2×22/7×1.4 = 8.8

Granite used in circle = 8.8 sq.m

Total granite used = 8.8+35 sq. m = 43.8 sq.m

Cost of granite used at per sq.m = Rs1200

Since, 1 sq. m = Rs 1200

So, 43.8 sq. m = Rs 1200× 43.8 = Rs 52560

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