Question

A metal pipe is $63cm$ long. Its inner diameter is $4cm$ and its outer diameter is $4.4cm$. Then it's the surface area of each end $=2.64c{m}^2$.

• A. True
• B. False

Answer 1

The correct option is A True

Calculations for surface area:

Surface area :
The outside part or uppermost layer of pipe

Length of pipe $\left(h\right)=63cm$

Inner diameter $\left(2r\right)=4cm\Rightarrow r=2cm$

Outer diameter $\left(2R\right)=4.4cm\Rightarrow R=2.2cm$

The surface area of each end $=\pi R^2-\pi r^2$

$$\begin{gathered} =\pi \left(R+r\right)(R-r) \\ =\frac{22}{7}(2.2+2)(2.2-2)\left(\pi =\frac{22}{7}\right) \\ =2.64c{m}^2 \end{gathered}$$

Hence, the statement is true.