# A cylindrical tube opened at both the ends is made of iron sheet which is 2 cm thick. If the outer diameter is 16 cm and its length is 100 cm, find how many cubic centimeters of iron has been used in making the tube?

**Solution:**

Given, a cylindrical tube is open at both ends

The tube is made of iron sheet 2 cm thick

The outer diameter of tube is 16 cm and length is 100 cm

We have to find how many cubic centimeters of iron has been used in making the tube.

Volume of cylindrical tube = πr²h

Where, r is the radius of the cylinder

h is the height of the cylinder

Volume of cylindrical tube = outer volume - inner volume

Given, outer radius r = 16/2 = 8 cm

h = 100 cm

Outer volume = π(8)²(100)

= π(64)(100)

= 6400π cm³

To find inner volume ,

Inner radius r = outer radius - 2 - 2 = 8 - 2 = 6 cm

h = 100 cm

Inner volume = π(6)²(100)

= π(36)(100)

= 3600π cm³

Volume of cylindrical tube = 6400π - 3600π

= (6400 - 3600)π

= 2800π

= 2800(22/7)

= 400(22)

= 8800 cm³

Therefore, the volume of iron used in making the tube is 8800 cm³.

**✦ Try This: **A cylindrical tube opened at both the ends is made of iron sheet which is 1.5 cm thick. If the outer diameter is 9 cm and its length is 70 cm, find how many cubic centimeters of iron has been used in making the tube?

**☛ Also Check: **NCERT Solutions for Class 9 Maths Chapter 13

**NCERT Exemplar Class 9 Maths Exercise 13.4 Problem 1**

## A cylindrical tube opened at both the ends is made of iron sheet which is 2 cm thick. If the outer diameter is 16 cm and its length is 100 cm, find how many cubic centimeters of iron has been used in making the tube?

**Summary:**

A cylindrical tube opened at both the ends is made of iron sheet which is 2 cm thick. If the outer diameter is 16 cm and its length is 100 cm, 8800 cubic centimeters of iron has been used in making the tube

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