Math, asked by Jessbass, 1 year ago

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

Answered by priyashagupta2007
0

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

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