The manager of a roofing company has two roofers, Alex and Brad. The manager wants to estimate the difference in average number of hours it takes to complete a job between these two workers. He takes a random sample of 31 jobs that Alex has completed and finds the mean number of hours is 16.7 with a standard deviation of 4.9. The random sample of 35 jobs that Brad has completed yields a mean of 20.6 hours with a standard deviation of 9.1 hours. Which is the 95% confidence interval for the difference (Alex – Brad) in mean number of hours to complete a roofing job?
Added by Laura M.
Step 1
7 Mean hours for Brad (x̄2) = 20.6 Difference in means (x̄1 - x̄2) = 16.7 - 20.6 = -3.9 Show more…
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