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A battery company claims that its batteries last an average of 100 hours under normal use....

A battery company claims that its batteries last an average of 100 hours under normal use. After several complaints that the batteries do not last this long, an independent testing laboratory decided to test the company’s claim with a random sample of 42 batteries. The data from the 42 batteries appeared to be unimodal and symmetric with a mean 97 hours and a standard deviation of 12 hours. Find a 90 % confidence interval for \muμ. Round your interval values out.

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Answer #1

from above 90% confidence interval for population mean =(93.884,100.116)

( please try 93.954, 100.046 if this comes wrong since sample size is 30 therefore z distribution can also be used)

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