(a)[1]
Write down an expression, in terms of $x$, for $CP$.
(b)[1]
Explain why $CQ = \left(\dfrac{80}{x} - 4\right)\,\text{cm}$.
(c)[3]
Show that the shaded area, $y\,\text{cm}^2$, can be written as $y = 32 + 2x + \dfrac{160}{x}$.
(d)[1]
Fill in the table for $y = 32 + 2x + \dfrac{160}{x}$. Where needed, give values to 1 decimal place.
(e)[3]
Using the grid, draw the graph of $y = 32 + 2x + \dfrac{160}{x}$ for $4 \le x \le 20$.
(f)[1]
Use the graph to determine the minimum possible shaded area.