Top Billers processes invoices forbusiness clients. Lately, Top Billers has been getting complaintsabout errors in the invoices they have processed. The qualitymanager for Top Billers decides to select one client at random eachday and sample all of that client’s invoices to measure the extentof the problem.
a)Ă‚Â Ă‚Â If the manager decidesto construct a u-chart, what values will be used for thecenter line, lower control limit, and the minimum and maximumvalues of the upper control limit of the control chart?
b)Ă‚Â Ă‚Â Create the controlchart.
c)Ă‚Â Ă‚Â Does the process appearto be in statistical control? Why or why not?
d)Ă‚Â Ă‚Â What conclusion can bedrawn about the overall quality of the service Top Billersoffers?
| No. of Invoices | No. of Invoices |
| Sample | Reviewed | With Errors |
| 1 | 171 | 2 |
| 2 | 194 | 1 |
| 3 | 121 | 3 |
| 4 | 200 | 0 |
| 5 | 159 | 1 |
| 6 | 162 | 3 |
| 7 | 186 | 4 |
| 8 | 182 | 1 |
| 9 | 155 | 2 |
| 10 | 185 | 2 |
| 11 | 179 | 4 |
| 12 | 160 | 3 |
| 13 | 159 | 1 |
| 14 | 154 | 1 |
| 15 | 151 | 2 |
| 16 | 169 | 0 |
| 17 | 189 | 3 |
| 18 | 178 | 4 |
| 19 | 161 | 2 |
| 20 | 198 | 1 |
| 21 | 174 | 1 |
| 22 | 120 | 2 |
| 23 | 152 | 3 |
| 24 | 166 | 4 |
| 25 | 182 | 3 |
| 26 | 185 | 2 |
| 27 | 161 | 5 |
| 28 | 129 | 1 |
| 29 | 170 | 4 |
| 30 | 143 | 1 |
