The average price of regular gasoline in continental US states and District of Columbia was $3.74 on August 18, 2008. Alaska and Hawaii aren't included as the gas prices there're much higher than continental US. The price of gasoline in eleven western states of US on the same day is given below. Test the hypothesis that the average price of gasoline in western states is higher than national average for Continental USA and District of Columbia, i.e., higher than $3.74. Employ 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 |