A cylindrical pillar has a radius of 21 cm and a height of 4 m. Find: The curved surface area of the pillar. cost of polishing 36 such cylindrical pillars at the rate of ₹12 per m2. - Mathematics

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Sum

A cylindrical pillar has a radius of 21 cm and a height of 4 m. Find:

  1. The curved surface area of the pillar.
  2. cost of polishing 36 such cylindrical pillars at the rate of ₹12 per m2.
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Solution

r = 21 cm, h = 4 m = 400 cm

i. C.S.A = 2πrh

= `2 xx 22/7 xx 21 xx 400`

= 52800 cm2

= `52800/(100 xx 100) = 5.28` m2

ii. Rate = ₹12/m2

Area to be polished = (5.28 × 36) m2

Cost = 12 × Area

= 12 × 5.28 × 36

= ₹2280.96

  Is there an error in this question or solution?
Chapter 21: Surface Area, Volume and Capacity - Exercise 21 (D) [Page 243]

APPEARS IN

Selina Concise Mathematics Class 8 ICSE
Chapter 21 Surface Area, Volume and Capacity
Exercise 21 (D) | Q 9 | Page 243
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