Gasoline pumped from a supplier€™s pipeline is supposed to have an octane rating of 87.5. On 13 consecutive days, a sample was taken and analyzed, with the following results.

a. If the octane ratings have a normal distribution, is there sufficient evidence to show that these octane readings were taken from gasoline with a mean octane significantly less than 87.5 at the 0.05 level? (The sample mean and standard deviation were found in answering Exercise 2.178, p.110.)
b. Did the statistical decision reached in part a result in the same conclusion you expressed in answering part c of Exercise 2.178 for these same data?

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