The external and internal radii of a hollow cylinder are 5 cm and 4 cm respectively. If the height of cylinder is 14 cm, then find its internal volume and total surface area.

Explanation

To solve the problem step by step, we will first find the internal volume of the hollow cylinder and then calculate its total surface area.

### Step 1: Calculate the Internal Volume
The formula for the volume \( V \) of a cylinder is given by:
\[ V = \pi r^2 h \]
where \( r \) is the internal radius and \( h \) is the height of the cylinder.
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