The Energy Information Administration of the U.S. Department of Energy provided time series data for the U.S. average price per gallon of conventional regular gasoline between July 2006 and June 2009 (Energy Information Administration website, June 2009). Use the Internet to obtain the average price per gallon of conventional regular gasoline since June 2009.

a. Extend the graph of the time series shown in Figure 1.1.

b. What interpretations can you make about the average price per gallon of conventional regular gasoline since June 2009?

c. Does the time series continue to show a summer increase in the average price per gallon? Explain.