The average price of regular gasoline in the continental US states and the District of Columbia was $3.74 on August 18, 2008. Alaska and Hawaii are not included as the gas prices there are much higher than the continental US. The price of gasoline in the eleven western states of the U.S. on the same day is given below. Test the hypothesis that the average price of gasoline in the western states is higher than the national average for Continental USA and the District of Columbia, i.e., higher than $3.74. Use level of significance a = 0.05.
California $4.04
Arizona $3.72
Colorado $3.83
Idaho $4.01
Montana $3.97
Nevada $3.84
New Mexico $3.77
Oregon $3.92
Utah $4.04
Washington $3.99
Wyoming $3.90