Chapter 14.1, Problem 58E

Spending on Gasoline From the beginning of 2007 to the beginning of 2014 the United States consumed gasoline at a rate of about

$q\left(t\right)=-1.2t+141\text{ billion gallons per year}\left(0\le t\le 7\right)$

(t is the year since 2007.)² During the same period of price of gasoline was approximately

$p\left(t\right)=3.5-2.38e^{-0.5t}\text{ dollars per gallon}$

Use an integral to estimate, to the nearest 10 billion dollars, the total spent on gasoline during the given period. [HINT: Rate of spending $=p\left(t\right)q\left(t\right)$.]