Based on a market survey, they found that the expectations are that customers would be happy if the guest check-in time is 100 ± 20 seconds. The hotel has been monitoring the process as follows:
As every guest arrives at the check-in desk, the elapsed time to complete the process is measured and recorded in a file.
Periodically, a sample of 100 such recordings are taken and those that exceeded 2 minutes were considered as defects.
This is used to set up a control chart.
A sample measurement is reproduced below:
Sample No. No. of defects
1 13
2 12
3 10
4 18
5 16
6 12
7 20
8 14
9 9
10 12
Meanwhile, a consultant who studied the process concluded that they were using an inappropriate control chart. The consultant recommended that since the detailed measurements of actual check-in time were being recorded it should be used to setup a control chart.
The hotel management was in alignment with the consultant's thinking and changed the type of control chart to X-bar chart. The process was monitored using it and found to be statistically stable. The mean of the guest check-in process was found to be 105 seconds and the standard deviation 8.
Using this information, answer the following question
Which of the following statements best describe the old process of measuring defects (prior to the change suggested by the consultant)?
The process was under statistical control
The process will on an average produce defects less than 10%
The control chart used was variable based control chart
The mean of the process was less than the standard deviation of the process