The Energy Information Administration (EIA), created by Congress in 1977, is a statistical agency of the U.S.

Department of Energy. It provides data, forecasts, and analyses to promote sound policymaking and public understanding regarding energy and its interaction with the economy and the environment. One of the most important areas of analysis is petroleum. The file entitled Crude contains data for the period 1991–2006 concerning the price, supply, and demand for fuel. It has been conjectured that the pricing structure of gasoline changed at the turn of the century.

a. Produce a regression equation to predict the selling price of gasoline:

b. Conduct a hypothesis test to address the conjecture.
Use a significance level of 0.05 and the test statistic approach.

c. Produce a 95% confidence interval to estimate the change of the average selling price of gasoline between the twentieth and the twenty-first centuries.

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where: = yi Bo+B+ if in twenty-first century 10 if in twentieth century