The outer and inner diameters of a hemispherical bowl are 17cm and 15cm find the cost of polishing it over at 25 paise ( Rs 25.14)
percm2
Answers
Answer:
the answer u have written on bracket is wrong
the answer of this question is Rs 100.48
Step-by-step explanation:
GIVEN :
The outer diameters of a hemispherical bowl D = 17 cm
The inner diameters of a hemispherical bowl d = 15 cm
The rate of polishing = 25 paisa per cm²
TO FIND :
The cost of polishing the hemispherical bowl
SOLUTION :
∵ The curved surface area of hemisphere = 2 π radius²
NOW,
Curved surface area of outer surface = 2 × π × R²
= 2 × π × (2 D)²
= 2 × 3.14 × ( 17 cm)²
= 1814.92 cm²
Curved surface area of inner surface = 2 × π × r²
= 2 × π × (2 d)²
= 2 × 3.14 × (15 cm)²
= 1413 cm²
Again
Curved surface area of ring = 2 × π × (R - r )²
= 2 × π × ( D² - d² )
= 2 × π × ( 17² - 15²)
= 2 × 3.14 × (289 - 225)
= 401.92 cm²
So, Total Surface area = Curved surface area of outer surface + Curved surface area of inner surface + Curved surface area of ring
i.e Total Surface area = 1814.92 cm² + 1413 cm² + 401.92 cm²
= 3629.84 cm²
Again
∵ The cost of painting 1 cm² = 25 paisa = Rs 0.25
∴ The cost of painting 401.92 cm² = Rs 0.25 × 401.92
= Rs 100.48