# CBSE Class 10-Mathematics: Chapter –13 Surface Areas and Volumes Part 9

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 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