The telecommunications manager at Lowell Call Center is concerned about the average difference in the downtime between day and night operations at the center.  A random sample of 45 day shifts and 45 night shifts shows that average downtime for the day shift sample is 53 minutes with a standard deviation of 18 minutes.  Average downtime for the night shift sample is 48 minutes with a standard deviation of 14 minutes.  Is the difference in sample average downtimes statistically significant at the 5% significance level?

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The telecommunications manager at Lowell Call Center is concerned about the average difference in the downtime between day and night operations at the center.  A random sample of 45 day shifts and 45 night shifts shows that average downtime for the day shift sample is 53 minutes with a standard deviation of 18 minutes.  Average downtime for the night shift sample is 48 minutes with a standard deviation of 14 minutes.  Is the difference in sample average downtimes statistically significant at the 5% significance level?

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Hypothesis Testing

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