Question 1161496: The manager of a warehouse store wants to estimate the average number of laser printer toner cartridges sold each day. A random sample of 37 days is selected and the sample mean is 115. The population standard deviation is estimated to be 9.8. Test the claim, using a 95% confidence interval for the mean, that the average number of laser printer toner cartridges sold each day is 110.
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website! half interval is z(0.975)*sigma/sqrt(n)
=1.96*9.8/sqrt(37)
=3.16
so the interval is (111.84, 118.16), adding and subtracting to and from the mean.
Because 110 is not in the interval, one rejects the claim. If 110 were in the claim, then we would be 95% confident that the true number could be 110, which is claimed.
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