Chapter 4.1, Problem 89E

Crude Oil Prices The price per barrel of crude oil in the period 1980-2013, in constant 2014dollars, can be approximated by

$P\left(t\right)=0.27t^2-8.6t+93\text{ dollars}\text{. }\left(0\le t\le 33\right).$

Where t is time in years since the start of 1980. Find $P^{\prime }\left(t\right)$

and $P^{\prime }\left(30\right)$. What does the second answer tell you about the price of crude oil? [HINT: See Example 2.]