In September 1995, the Automobile Confederation of the Carolinas surveyed 75 randomly chosen service stations in North and South Carolina and determined that the average price for regular unleaded gasoline at self-service pumps was $1.059, and the sample standard deviation was 3.9¢. Three months later, another survey of 50 service stations found an average price of $1.089, and the sample standard deviation was 6.8¢. At α = 0.02, had the Carolinas’ average price of self-service regular unleaded gasoline changed signifi cantly in this 3-month period?
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