Researchers at the Mayo Clinic have studied the effect of sound levels on patient healing and have found a significant association (louder hospital ambient sound level is associated with slower postsurgical healing). Based on the Mayo Clinic's experience, Ardmore Hospital in- stalled a new vinyl flooring that is supposed to reduce the mean sound level (decibels) in the hospital corridors. The sound level is measured at five randomly selected times in the main corridor.
(a) At α = .05, has the mean been reduced? Show the hypotheses, decision rule, and test statistic.
(b) At α = .05, has the variance changed? Show the hypotheses, decision rule, and test statistic.

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