4 The Exhibition Centre hires a graphics company to produce a poster for an exhibit. The graphics company charges $\$ 1000$ and an additional $\$ 5$ for each poster produced.
a i Write down the rule for a function, $C(n)$, which describes the cost to the Exhibition Centre of obtaining $n$ posters.
ii Sketch the graph of $C$ against $n$. (Use a continuous model.)
b The Exhibition Centre is going to sell the posters for $\$ 15$ each.
i Write down the rule for a function, $P(n)$, which describes the profit when the Exhibition Centre sells $n$ posters.
ii Sketch the graph of $P$ against $n$. (Use a continuous model.)
Answer
Sketch P(n) with slope 10 and y-intercept -1000
Step 1 ：C(n) = 1000 + 5n
Step 2 ：Sketch C(n) with slope 5 and y-intercept 1000
Step 3 ：P(n) = 10n - 1000
Step 4 ：Sketch P(n) with slope 10 and y-intercept -1000
