Question

A local bank wants to study waiting times of customers. A subgroup of four customers is selected, and the time is measured from the point each customer enters the line to when he or she reaches the teller window. The results are shown in the data table. (a) Construct control charts for the range and the mean. (b) Is the process in control? EB Click the icon to view the data. Click the icon to view a table of control chart factors (a) Construct a control chart for the range. Choose the correct graph below. O A. O B. Ос. 20 20 20 20 7.5 5.6 5.5 3.5 9.8 8.8 5.6 8.8 5.8 3.9 2.8 4.1 8.6 7.1 Time in minutes 9.7 8.6 8.9 8.2 4.6 9.2 5.9 5.5 4.8 7.8 3.3 3.5 5.5 4.7 9.8 5.6 8.4 4.9 6.1 5.8 7.5 5.5 8 4.8 4.8 4.5 1.3 9.7 5.4 7.2 9.5 4.9 8.4 6.4 6.1 10 3.3 3.8 12 13 14 15 16 17 18 19 20 6.6 5.3 4.9 7.2 6.1 6.5 6.4 5.7 6.9 6.4 5.2 8.1 6.6 9.5 8.4 6.7 6.8 3.1 2.7 3.9 Number of Observations in Sample/Subgroup (n) 0.853 0.888 0.880 0.864 0.848 0.833 0.820 0.808 3.267 2.575 1.128 1.880 1.023 2.059 2.326 2.534 2.704 2.847 2.970 3.078 3.173 3.258 3.336 3.407 0 0 0 0.076 0.136 0.184 0.223 0.256 0.283 0.307 0.328 0.347 0.363 0.378 0.391 0.404 0.415 0.577 0.483 0.419 0.373 0.337 0.308 0.285 0.266 0.249 0.235 0.223 0.212 0.203 0.194 0.187 0.180 2.114 2.004 1.924 1.864 0.787 1.744 12 0.770 0.763 0.756 0.750 0.744 0.739 0.733 0.729 0.724 1.672 15 3.532 3.588 3.640 3.689 3.735 3.778 3.819 3.858 3.895 3.931 1.637 1.622 1.609 1.596 1.585 1.575 1.565 1.557 1.548 1.541 17 20 0.435 0.443 0.452 0.459 0.167 0.162 0.157 0.153 0.712 0.708 25 Number of Observations in Sample/Subgroup (n)

Answer 1

We will use MINITAB software to answer this question.

a)

R Chart of each day UCL 7.688 R-3.370 e辦 LCL-O 1 3 5 7911 13 15 17 19 Sample

So the correct option is D

b) the range is in control as per the chart ( all points are withing the control limits)

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