Answer
(a) $R(9)=\$4.7$; $C(9)=\$10.8$
(b) $P(t)=0.6t-11.5$
(c) $P(9)=-\$6.1$
Work Step by Step
$R(t)=1.3t-7.0$
$C(t)=0.7t+4.5$
(a)
Put $t=2009-2000=9$ in the above equations:
$R(9)=1.3\times9-7.0=4.7$
$C(9)=0.7\times9+4.5=10.8$
(b)
Let $P(t)$ be the profit function of $t$.
$P(t)=R(t)-C(t)$
$P(t)=1.3t-7.0-(0.7t+4.5)$
$P(t)=1.3t-7.0-0.7t-4.5$
$P(t)=1.3t-0.7t-7.0-4.5$
$P(t)=0.6t-11.5$
(c)
Put $t=9$ in
$P(t)=0.6t-11.5$
$P(9)=0.6\times9-11.5=-6.1$
Negative sign indicates the loss.
