**INDUSTRY AND COMPANY AWARENESS (ICA)**

A hollow iron pipe is 21 cm long and its external diameter is 8 cm. If the thickness of the pipe is 1 cm and iron weighs 8 g/cm^{3}, then the weight of the pipe is:

**Answer: Option B**

External radius = 4 cm,

Internal radius = 3 cm.

Volume of iron = \(\left(\frac{22}{7}\times\left[(4)^{2}-(3)^{2}\right]\times21

\right)cm^{3}\)

= \(\left(\frac{22}{7}\times7\times1\times21\right)cm^{3}\)

= 462 cm^{3}.

So, Weight of iron = (462 x 8) gm = 3696 gm = 3.696 kg.

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