The water pollution readings at State Park Beach seem to be lower than those of the prior year. A sample of 12 readings (measured in coliform/100 mL) was randomly selected from the records of this year€™s daily readings:

Does this sample provide sufficient evidence to conclude that the mean of this year€™s pollution readings is significantly lower than last year€™s mean of 3.8 at the 0.05 level? Assume that all such readings have a normal distribution.

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3.5 3.9 2.8 3.1 3.1 3.4 4.8 3.2 2.5 3.5 44 3.