A hemispherical bowl made of brass has inner diameter 10.5cm. Find the cost of tin-plating it on the inside at the rate of Rs 16 per 100 cm2. -Maths 9th

A hemispherical bowl made of brass has inner diameter 10.5cm. Find the cost of tin-plating it on the inside at the rate of Rs 16 per 100 cm2. -Maths 9th
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1 Answer

Answer :

Inner radius of hemispherical bowl, say r = diameter/2 = (10.5)/2 cm = 5.25 cm Formula for Surface area of hemispherical bowl = 2πr2 = 2×(22/7)×(5.25)2 = 173.25 Surface area of hemispherical bowl is 173.25 cm2 Cost of tin-plating 100 cm2 area = Rs 16 Cost of tin-plating 1 cm2 area = Rs 16 /100 Cost of tin-plating 173.25 cm2 area = Rs. (16×173.25)/100 = Rs 27.72 Therefore, the cost of tin-plating the inner side of the hemispherical bowl at the rate of Rs 16 per 100 cm2 is Rs 27.72.
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