# CBSE Class 10-Mathematics: Chapter –13 Surface Areas and Volumes Part 22

Doorsteptutor material for CBSE is prepared by world's top subject experts: fully solved questions with step-by-step explanation- practice your way to success.

**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.

**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