NumericalModerate3 marks
A hollow sphere of external diameter 10 cm and internal diameter 6 cm is melted and made into a solid right circular cone of height 8 cm. Find the radius of the cone so formed. (Use π = 22/7)
Topic: Mensuration
Previous-year question practice database
Answer
Exam answer
Radius of cone = 7 cm.
Explanation
Volume hollow sphere=(4/3)π(5³−3³)=(392/3)π. Cone volume=(1/3)πr²·8. Equating gives 8r²=392 ⇒r=7.
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