The Energy Information Administration published a press release on September 26, 2005 (Paula Weir and Pedro Saavedra, “Two Multi-Phase Surveys That Combine Overlapping Sample Cycles at Phase I”). The file titled Diesel$ contains the average on-highway diesel prices for each of 53 weeks from September 27, 2004, to September 26, 2005. It also contains equivalent information for the state of California, recognized as having the highest national prices.
a. Construct a chart containing line plots for both the national average and California’s diesel prices. Describe the relationship between the diesel prices in California and the national average.
b. In what week did the California average diesel price surpass $3.00 a gallon?
c. Determine the smallest and largest price paid in California for a gallon of diesel. At what weeks did these occur? Use this information to project when California gas prices might exceed $4.00, assuming a linear trend between California diesel prices and the weeks in which they occurred.