The outer and inner diameters of a hemispherical bowl are 17cm and 15cm. Find the cost of polishing it all over at Rs 2.50 per cm2
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The outer and inner diameters of a hemispherical bowl are 17cm and 15cm. Find the cost of polishing it all over at Rs 2.50 per cm2
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Given:
Outer diameter (D) = 17cm
Inner diameter (d) = 15cm
Cost of polishing it per cm² = ₹2.50
To find:
Total surface of the hemispherical bowl.
The cost of polishing it all over at Rs 2.50 per cm²
Solution:
First we will find the C.S.A. of inner bowl
So, this implies 2πr²
2×22/7×(15)²
44/7×225
1414.3 cm²
Also the C.S.A of outer bowl = 2πR²
So, this implies 2×22/7×(17)²
44/7×289
1816.6 cm²
Now, the area of its ring = 2π(R-r)²
So, this implies 2×22/7×(17-15)²
44/7×(2)²
44/7×4
176/7
25.1 cm²
Now, Total surface area of the hemispherical bowl = C.S.A. of the outer bowl + C.S.A. of the inner bowl + Area of its ring
So, this implies 1414.3 + 1816.6 + 25.1 = 3256 cm²
So, The cost of polishing 3256 cm²= ₹2.50×3256
= ₹8,140
Hence the cost of polishing it all over = ₹8140
Hope it helps you.
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