A cylindrical container of radius 6 cm and height 15 cm is filled with ice-cream. The whole ice-cream has to be distributed to 10 children in equal cones with hemispherical tops. If the height of the conical portion is 4 times the radius of its base, find the radius of the ice-cream cone.

Radius of cylindrical container = r = 6 cm


Height of cylindrical container = h = 15 cm


Volume of cylindrical container = πr2h


= 22/7 × 6 × 6 × 15 cm3


= 1697.14 cm3


Whole ice-cream has to be distributed to 10 children in equal cones with hemispherical tops.


Let the radius of hemisphere and base of cone be r’


Height of cone = h = 4 times the radius of its base


h’ = 4r’


Volume of Hemisphere = 2/3 π(r’)3


Volume of cone = 1/3 π(r’)2h’ = 1/3 π(r’)2 × 4r’


= 2/3 π(r’)3


Volume of ice-cream = Volume of Hemisphere + Volume of cone


= 2/3 π(r’)3 + 4/3 π(r’)3 = 6/3 π(r’)3


Number of ice-creams = 10


total volume of ice-cream = 10 × Volume of ice-cream


= 10 × 6/3 π(r’)3 = 60/3 π(r’)3


Also, total volume of ice-cream = Volume of cylindrical container


60/3 π(r’)3 = 1697.14 cm3


60/3 × 22/7 × (r’)3 = 1697.14 cm3


(r’)3 = 1697.14 × 3/60 × 7/22 = 27 cm3


r = 3 cm


Radius of ice-cream cone = 3 cm


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