A manager of an e-commerce company would like to determine average delivery time of the products....

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A manager of an e-commerce company would like to determineaverage delivery time of the products. A sample of 25 customers istaken. The average delivery time in the sample was four days with astandard deviation of 1.2 days. Suppose the delivery times arenormally distributed.
Provide a 95 % confidence interval for the mean deliverytime.
The manager claims that the average delivery time of theirproducts does not exceed 3 days. Write the null and alternativehypothesis regarding to the claim ofÂ Â the manager.
Test the managerâ€™s claim at 95 % confidence level.
For an effective parental skill study, a researcher asked: Howmany hours do your kids watch the television during a typical weekin Barcelona? The mean of 100 Kids (ages 6-11) spend about 28 hoursa week in front of the TV. Suppose the study follows a normaldistribution with standard deviation 5.
Estimate the mean of all kids (ages 6-11) in Barcelona, using99% confidence interval. (show all the calculations)
Write the conclusion of your result

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4.0 Ratings (677 Votes)

aHere n25 4 s12Let the population mean be The test statistic follows t distribution with dfn124Hence the 95 confidence interval is 350464449536bThe null and the alternative See Answer

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