A competitive firm has the following short-run cost function: $C(q)=q^{3}-8 q^{2}+30 q+5$
a. Find $\mathrm{MC}, \mathrm{AC}$, and $\mathrm{AVC}$ and sketch them on a graph.
b. At what range of prices will the firm supply zero output?
c. Identify the firm's supply curve on your graph.
d. At what price would the firm supply exactly 6