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The hemispherical dome of a building needs to be painted (see Fig. 14.16). If the circumference of the base of the dome is 35.2 m, find the cost of painting it, given the cost of painting is ₹10 per 100 cm².

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Base circumference 2πr = 35.2 m gives r = 5.6 m. Outer surface area is 2πr² = 197.12 m² = 1,971,200 cm². At ₹10 per 100 cm², the painting cost is 19,712 × 10 = ₹1,97,120.

Class 9 Ganita Manjari part 2 Chapter 14.4 Solutions
Class 9 Ganita Manjari Part II Chapter 14 Page 140 Question Answer

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1 Answer

  1. Given base circumference 2πr = 35.2 m, using π = 22/7 gives r = (35.2 × 7) / 44 = 5.6 m. The curved surface area of the dome is 2πr² = 2 × (22/7) × (5.6)² = 197.12 m². Converting to cm² gives 197.12 × 10,000 = 1,971,200 cm². At the rate of ₹10 per 100 cm², the cost is (1,971,200 / 100) × 10 = ₹1,97,120.

     

    For more NCERT Solutions of Class 9 Maths Ganita Manjari Part 2 Chapter 14 Math of Space: Surface Area and Volume Question Answer (2026-27)

    https://www.tiwariacademy.com/ncert-solutions/class-9/maths/ganita-manjari-chapter-14/

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