Track Bicycle Parts manufactures precision ball bearings for wheel hubs, bottom brackets, head sets, and pedals. Seth Adams is responsible for quality control at Track. He has been checking the output of the 5-mm bearings used in front wheel hubs. For each of the last 18 hours, he has sampled 5 bearings, with the following results:
| Batch | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 |
| Hour | Bearing Diameters (mm) | ||||||||||||||
| 1 | 5.03 | 5.06 | 4.86 | 4.90 | 4.95 | ||||||||||
| 2 | 4.97 | 4.94 | 5.09 | 4.78 | 4.88 | ||||||||||
| 3 | 5.02 | 4.98 | 4.94 | 4.95 | 4.80 | ||||||||||
| 4 | 4.92 | 4.93 | 4.90 | 4.92 | 4.96 | ||||||||||
| 5 | 5.01 | 4.99 | 4.93 | 5.06 | 5.01 | ||||||||||
| 6 | 5.00 | 4.95 | 5.10 | 4.85 | 4.91 | ||||||||||
| 7 | 4.94 | 4.91 | 5.05 | 5.07 | 4.88 | ||||||||||
| 8 | 5.00 | 4.98 | 5.05 | 4.96 | 4.97 | ||||||||||
| 9 | 4.99 | 5.01 | 4.93 | 5.10 | 4.98 | ||||||||||
| 10 | 5.03 | 4.96 | 4.92 | 5.01 | 4.93 | ||||||||||
| 11 | 5.02 | 4.88 | 5.00 | 4.98 | 5.09 | ||||||||||
| 12 | 5.09 | 5.01 | 5.13 | 4.89 | 5.02 | ||||||||||
| 13 | 4.90 | 4.93 | 4.97 | 4.98 | 5.12 | ||||||||||
| 14 | 5.04 | 4.96 | 5.15 | 5.04 | 5.02 | ||||||||||
| 15 | 5.09 | 4.90 | 5.04 | 5.19 | 5.03 | ||||||||||
| 16 | 5.10 | 5.01 | 5.04 | 5.05 | 5.02 | ||||||||||
| 17 | 4.97 | 5.10 | 5.12 | 4.92 | 5.04 | ||||||||||
| 18 | 5.01 | 4.99 | 5.06 | 5.04 | 5.12 | ||||||||||
- (a) Construct an x chart to help Seth determine whether the production of 5-mm bearings is
in-control.
- Should Seth conclude that the process is in-control? Explain.
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