Question

# A Hollow cylindrical pipe is 21 cm long. If its outer and inner diameters are 10 cm and 6 cm respectively, then find the volume of the metal used in making the pipe?

Hint:

### We find the inner and outer radius of the pipe. Then calculate the volume of the pipe using both the radius. At last, we subtract the volume with inner radius from the volume with outer radius to find the volume of metal.

## The correct answer is: The volume of metal used in making the pipe is 1056 cm3.

### Explanations:

Step 1 of 3:

The outer and inner diameters of the hollow cylindrical pipe are given by, 10 cm and 6 cm.

Then, the outer and inner radius are 5 cm(= R) and 3 cm(= r).

The pipe is 21 cm(= h) long.

Step 2 of 3:

The volume with outer radius is cm^{3}

The volume with inner radius is cm^{3}

Step 3 of 3:

Volume of metal used to make the pipe is cm^{3}

Final Answer:

The volume of metal used in making the pipe is 1056 cm^{3}.

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