Question

A hemispherical bowl is made of brass, 0.25 cm thickness. The inner radius of the bowl is 5 cm. Find the ratio of outer surface area to inner surface area.

Answer 1

Inner radius of the hemisphere ‘r’ = 5 cm 

Outer radius of the hemisphere ‘R’ 

= inner radius + thickness 

= (5 + 0.25) cm = 5.25 cm 

Ratio of areas = 3πR² : 3πr² 

= R² : r² 

= (5.25)² : 5² 

= 27.5625 : 25 

= 1.1025:1 

= 11025 : 10000 

= 441 : 400