Mathematics
A hemi-spherical bowl (as shown) has external radius R and internal radius r, the outer surface area of the bowl is :
2πR2 + πr2
3πR2 - πr2
2πR2 + 2πr2
2πR2 - πr2
Mensuration
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Answer
Outer surface area of the hemi-spherical bowl = Surface area of outer hemisphere + Area of outer cross-section - Area of inner cross-section
= 2πR2 + πR2 - πr2
= 3πR2 - πr2.
Hence, Option 2 is the correct option.
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