Question

The diameter of a solid pipe is 4 cm whose length is 20 cm. Then the volume of the metal used in the pipe will be

• A. $20\pi \, \text{cm}^3$
• B. $10\pi \, \text{cm}^3$
• C. $140\pi \, \text{cm}^3$
• D. $80\pi \, \text{cm}^3$

Hint:

Volume of a cylinder is $\pi r^2 h$. Always convert diameter to radius before applying the formula.

Answer 1

The Correct Option is D

Step 1: Given data.
Diameter = 4 cm → Radius = 2 cm, \; Length = 20 cm.
Step 2: Formula for volume of cylinder.
Volume $V = \pi r^2 h$
\[ V = \pi (2)^2 (20) = \pi \times 4 \times 20 = 80\pi \, \text{cm}^3 \] Step 3: Conclusion.
Hence, the volume of the solid pipe = $80\pi \, \text{cm}^3$.