Dick Burney is director of 911 emergency medical services in Ann Arbor, Michigan. He is concerned about response time, the amount of time that elapses between the receipt of a call at the 911 switchboard and the arrival of a municipal rescue squad crew at the calling location. For the last 3 weeks, he has randomly sampled response times for 9 calls each day to get the following results, with x ̅ and R measured in minutes:
| Batch | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 |
| x | 15.85 | 15.95 | 15.86 | 15.84 | 15.91 | 15.81 | 15.86 | 15.84 | 15.83 | 15.83 | 15.72 | 15.96 | 15.88 | 15.84 | 15.89 |
| R | 0.15 | 0.17 | 0.18 | 0.16 | 0.14 | 0.21 | 0.13 | 0.22 | 0.19 | 0.21 | 0.28 | 0.12 | 0.19 | 0.22 | 0.24 |
- Use the data above to help Jeff construct an x chart.
- Is the production process in-control? Explain
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