1-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.Suppose the delivery times are normally distributed with a standarddeviation of 1.2 days.
a) Provide a 95 % confidence interval for the mean deliverytime.
b) The manager claims that the average delivery time of theirproducts does not exceed 3 days. Write the null and alternativehypothesis regarding to the claim of the manager.
c) Test the manager’s claim at 95 % confidence level.
d) Write the conclusion of your result 3)
2- For an effective parental skill study, a researcher asked:How many hours do your kids watch the television during a typicalweek in Barcelona? The mean of 100 Kids (ages 6-11) spend about 28hours a week in front of the TV. Suppose the study follows a normaldistribution with standard deviation 5.
a) Estimate the mean of all kids (ages 6-11) in Barcelona, using99% confidence interval. (show all the calculations)
b) Write the conclusion of your result
