# 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.

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.

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 ?

Volume of the cuboid

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.