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The score on a proficiency measure is assumed to follow a normal distribution. A switch to...

The score on a proficiency measure is assumed to follow a normal distribution. A switch to better lighting might change the score. A random sample of 30 people taken during the year before the switch to better light yielded a mean score of 600 and a variance of 400. A different random sample of 30 people after the switch had a mean of 610 and a variance of 441. Important: use a degrees of freedom nu=80 for the t statistic.

Suppose it was really the same people before and after the change in lighting and that that the average improvement in score was 10.5 with a sample standard deviation of 20. Now, does the change in lighting seem to have changed the proficiency score? Show your work and explain using one or two sentences.

Math   Statistics-And-Probability   
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