Solved UPSC CDS/OTA Question
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Q · Mensuration Medium · 45s
The radius of the hemisphere is thrice that of a sphere. What is the ratio of total surface
TopicMensuration
Question Typemultiple choice
DifficultyMedium
Marking+1 / −0.33
Test Duration30 min
Step-by-Step Solution
The complete worked solution.
Every step explained - no skipped algebra.
Radius of sphere=r
Radius of hemisphere=3r
Area of sphere of radius r = 4πr₂
Area of Hemisphere of radius r = Area of curved surface + Area of flat surface =
2πr₂ + πr₂ = 3πr₂
Required ratio=3π(3r)2 :4πr₂ =27:4
Final Answer: Option A - 27 : 8