The owner of a restaurant has just changed the delivery process in order to reduce the mean time between the order and completion of delivery from the current 25 minutes. In the past, the population standard deviation has been 6 minutes. A sample of 36 orders under the new delivery process results in a sample mean of 22.4 minutes.
1. Using the 6-step critical value approach, at the 0.05 level of significance, is there support that the population mean delivery time has been lessened below the prior population mean value of 25 minutes?
2. At the 0.05 level of significance, use the 5-step p-value approach.
3. Interpret the meaning of the p-value in question 2.
4. Compare the conclusions in questions 1 and 2.
The solution provides step by step method for the calculation of testing of hypothesis. Formula for the calculation and Interpretations of the results are also included. Interactive excel sheet is included. The user can edit the inputs and obtain the complete results for a new set of data.