# 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 Rs 16 per 100 cm^2. - Mathematics

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 Rs 16 per 100 cm2.

["Assume "pi=22/7]

#### 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 = Rs. 16

Cost of tin-plating 173.25 cm2 area= Rs.(16xx173.25)/100

= Rs 27.72

Therefore, the cost of tin-plating the inner side of the hemispherical bowl is Rs. 27.72.

Concept: Surface Area of a Sphere
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#### APPEARS IN

NCERT Class 9 Maths
Chapter 13 Surface Area and Volumes
Exercise 13.4 | Q 5 | Page 225