# CBSE Class 10-Mathematics: Chapter – 13 Surface Areas and Volumes Part 9 (For CBSE, ICSE, IAS, NET, NRA 2022)

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**Question 9**:

How many silver coins, in diameter and of thickness , must be melted to form a cuboid of dimensions ?

**Answer**:

cm and Thickness

For cuboid, Length , Breadth and Height

Let coins be melted.

Then, According to question,

Volume of coins Volume of cuboid

Unless stated otherwise, take .

**Question 10**:

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

**Answer**:

Abbreviation: CSA Curved Surface Area

TSA Total Surface Area

V Volume

Here,

Capacity of the glass

**Question 11**:

The slant height of a frustum of a cone is and the perimeters (circumference) of its circular ends are and . Find the curved surface area of the frustum.

**Answer**:

Let be the radii of the ends of the frustum of the cone.

Then,

Now, CSA of the frustum

**Question 12**:

A fez, the cap used by the Turks, is shaped like the frustum of a cone (see figure) . If its radius on the open side is , radius at the upper base is and its slant height is , find the area of material used for making it.

**Answer**:

Here,

Surface area