A bank manager decides to study waiting times of customers for teller service at the noon lunch hour (noon to 1pm). He selects one customer every 20 minutes to

Question

A bank manager decides to study waiting times of customers for teller service at the noon lunch hour (noon to 1pm). He selects one customer every 20 minutes to measure the time the customer enters the line to the time he or she reaches the teller window. He records this over several days.

 

Example Data

 

Day          Time in Minutes

1                   7.2        8.4        7.9

2                   5.6        8.7        3.3

3                   5.5        7.3        3.2

4                   4.4        8.0        5.4

5                   9.7        4.6        4.8

6                   8.3        8.9        9.1

 

1. What are the values of X-Bar for each day?

2. What are the values of the ranges for each day?

3. What is the grand mean for the X-Bar data?

4. What is the average of the range values?

5. Compute the values for the upper and lower control limits for both the upper and lower plotting areas.

6. Plot the Control Chart.

7. Are there any signals of special cause variation?

Please work this problem out by hand/excel first and then plot the Xbar-R chart in excel and compare your results.

Answer 1

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