CBSE Class 10-Mathematics: Chapter –13 Surface Areas and Volumes Part 22
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Question 25:
Metallic sphere of radii , and respectively are melted to form a single solid sphere. Find the radius of the resulting sphere.
Answer:
Sum of the volumes of three given spheres
Let R be the radius of single solid sphere, since volume remains the same
Question 26:
A shuttle cock used for playing badminton has the shape of a frustum of a cone mounted on a hemisphere. The external diameter of the frustum is and . The height of the entire shuttle cock is . Find the external surface area.
Answer:
External surface area. of frustum of the come . of hemisphere
Question 27:
How many silver coins in diameter and of thickness must be melted to form a cuboid ?
Answer:
Volume of the cuboid
Radius of the coin
Thickness
Volume of one coin
Required number of coins
Question 28:
A container like a right circular having diameter and height is full of ice-cream. The ice-cream is to be filled in cones of height and diameter 6cm having a hemispherical shape on the top. Find number of such cones which can be filled with ice-cream.

Find Number of Such Cones
Answer:
Volume of cylinder
Diameter of
Volume of ice cream Volume of ice-cream cone Volume of hemispherical top of ice-cream
Number of ice-Cream cones