# CBSE Class 10-Mathematics: Chapter – 13 Surface Areas and Volumes Part 12 (For CBSE, ICSE, IAS, NET, NRA 2022)

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**Question 21**:

The height of a right circular cone is and the radius of its base is . Find its slant height.

**Answer**:

Slant height

**Question 22**:

How many balls, each of radius 1cm, can be made from a solid sphere of lead of radius .

**Answer**:

Number of balls

**Question 23**:

A drinking glass is in the shape of a frustum of a cone of height . The diameter of its two circular ends are and m. Find the capacity of the glass.

**Answer**:

Capacity of glass

**Question 24**:

The diameter of a sphere is . It is melted and drawn into a wire of diameter . What is the length of wire?

**Answer**:

Radius of sphere

Volume of sphere

Let length of the wire R = Radius of the wire Volume of wire

**Question 25**:

An iron pipe long has exterior diameter equal to . If the thickness of the pipe is . Find the whole surface area of the pipe.

**Answer**:

Total surface area of pipe

**Question 26**:

Find the ratio of the volumes of two circular cones. If .

**Answer**:

Ratio of volumes of two cones