The file P08_06.xlsx contains data on repetitive task times foreach of two workers. John has been doing this task for months,whereas Fred has just started. Each time listed is the time (inseconds) to perform a routine task on an assembly line. The timesshown are in chronological order. a. Calculate a 95% confidenceinterval for the standard deviation of times for John. Do the samefor Fred. What do these indicate? b. Given that these times arelisted chronologically, how useful are the confidence intervals inpart a? Specifically, is there any evidence that the variation intimes is changing over time for either of the two workers? Pleaseprovide it as per the Excel.
| Observation | John | Fred |
| 1 | 66.4 | 75.6 |
| 2 | 63.8 | 75.1 |
| 3 | 69.3 | 74.6 |
| 4 | 64.2 | 76.1 |
| 5 | 55.7 | 71.6 |
| 6 | 72.5 | 73.7 |
| 7 | 66.2 | 75.8 |
| 8 | 64.0 | 81.8 |
| 9 | 68.3 | 73.3 |
| 10 | 66.1 | 73 |
