The price per barrel of crude oil in the period 1980-2013, in constant 2014 dollars, can be approximated by P(t) = 0.27+ - 8.6t + 93 dollars (0 t 33), where t is time in years since the start of 1980.+ Find P'(t) and P'(31). P'(t) = P'(31) = $ per year What does the second answer tell you about the price of crude oil? Hint [See Example 2.] The price of a barrel of crude oil was increasing at a rate of $ per year in