(a)[3]
Demonstrate that the prism has volume, $V\text{ cm}^3$, given by $V = 40x - 5x^2$.
(b)[3]
On the grid on the following page, plot the graph of $V = 40x - 5x^2$ for $1 \le x \le 7$; three points are already marked.
(c)[2]
From the graph, determine the possible values of $x$ for one of these prisms when the volume is $50\text{ cm}^3$.
(d)[3]
A cuboid measures $4\text{ cm}$ by $3\text{ cm}$ by $x\text{ cm}$. By adding an appropriate line to your graph, find $x$ when the prism and the cuboid have equal volumes.