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Question
A hemispherical bowl made of brass has inner diameter 10.5 cm. Find the cost of tin-plating it on the inside at the rate of ₹ 16 per 100 cm2.
`["Assume "pi=22/7]`
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Solution
Inner radius (r) of hemispherical bowl = `(10.5/2) cm` = 5.25 cm
Surface area of hemispherical bowl = 2πr2
= `[2xx22/7xx(5.25)^2]cm^2`
= 173.25 cm2
Cost of tin-plating 100 cm2 area = ₹ 16
Cost of tin-plating 173.25 cm2 area = `₹ (16 xx 173.25)/100`
= ₹ 27.72
Therefore, the cost of tin-plating the inner side of the hemispherical bowl is ₹ 27.72.
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