Homework Sourse63 The time to replace vehicle wiper blades at a service cen
6.3
The time to replace vehicle wiper blades at a service center was monitored using a mean and a range chart. Six samples of n = 20 observations have been obtained and the sample means and ranges computed:
FACTORS FOR R CHARTS
Using the factors in the above table, determine upper and lower limits for mean and range charts. (Do not round intermediate calculations. Round your mean value to 3 decimal places and range value to 4 decimal places.)
| The time to replace vehicle wiper blades at a service center was monitored using a mean and a range chart. Six samples of n = 20 observations have been obtained and the sample means and ranges computed: |
Solution
a.
b.
Yes, process is under control because data collected from samples are within the control limits of mean and range.
| Sample | Mean | Range | Average | Center | Lower Control Limil | Upper control Limil | Range | Center | Lower Control Limit | Upper Control Limit |
| 1 | 3.06 | 0.42 | 3.06 | 3.1 | 3.019 | 3.181 | 0.42 | 0.45 | 0.1845 | 0.7155 |
| 2 | 3.15 | 0.5 | 3.15 | 3.1 | 3.019 | 3.181 | 0.5 | 0.45 | 0.1845 | 0.7155 |
| 3 | 3.11 | 0.41 | 3.11 | 3.1 | 3.019 | 3.181 | 0.41 | 0.45 | 0.1845 | 0.7155 |
| 4 | 3.13 | 0.46 | 3.13 | 3.1 | 3.019 | 3.181 | 0.46 | 0.45 | 0.1845 | 0.7155 |
| 5 | 3.06 | 0.46 | 3.06 | 3.1 | 3.019 | 3.181 | 0.46 | 0.45 | 0.1845 | 0.7155 |
| 6 | 3.09 | 0.45 | 3.09 | 3.1 | 3.019 | 3.181 | 0.45 | 0.45 | 0.1845 | 0.7155 |
| Average | 3.1 | 0.45 | ||||||||
| A2= | 0.18 | |||||||||
| D3 = | 0.41 | |||||||||
| D4 = | 1.59 | |||||||||
| Upper limit for mean | 3.181 | |||||||||
| Lower limit for mean | 3.019 | |||||||||
| Upper limit for range | 0.7155 | |||||||||
| Lower limit for range | 0.1845 |
