Question 1
The following chart represents your sandwich prep time IMR control charts set of your sandwich process. You are the Lead Green Belt of a Quality Assurance Team that will report the findings to the management. Interpret the charts for Ms. Nguyen, your district manager.
Question 2
Use the following data decide if the outcome of an operation depends on the process used
| Condition | Process A | Process B | Process C | Process D | Process E |
| No improvement | 13 | 5 | 8 | 21 | 43 |
| Partial improvement (less than goal) | 18 | 10 | 36 | 56 | 29 |
| Met improvement goal | 16 | 16 | 35 | 51 | 10 |
Solution
Question 3 (
Gabriel is working on a project to address the root cause of defective sub-assemblies. It has been brought to Gabriel’s attention that a higher percentage of defectives are produced in the third shift. Gabriel collected the following data to check the validity of the above claim:
Test at 5% significance level to determine if the proportion of defectives is the same for all three shifts
| TYPE | First Shift | Second Shift | Third Shift |
| Defectives | 43 | 56 | 68 |
| Non-Defectives | 965 | 878 | 781 |
Solution
Question 4
The customer expectation when phoning a customer service line is that the average amount of time from completion of dialing until they hear the message indicating the time in queue is equal to 55.0 seconds (less than a minute was the response from customers surveyed, so the standard was established at 10% less than a minute).
You decide to randomly sample at 20 times from 11:30am until 9:30pm on 2 days to determine what the actual average is. The actual data was as follows:
54.1, 53.3, 56.1, 55.7, 54.0, 54.1, 54.5, 57.1, 55.2, 53.8,54.1, 54.1, 56.1, 55.0, 55.9, 56.0 ,54.9, 54.3, 53.9, 55.0
What is a 95% confidence interval for the true mean call completion time?
What is the 95% confidence interval on the standard deviation
Solution
Question 5
The following data represent the value of a certain quality characteristic of interest during a LSS improvement project. Using your knowledge in SPC as Green Belt, please interpret the data and statistically state your case for Ms. Nguyen your district Manager
| # | Date | Stage | Project Metric |
| 1 | 4/13/2015 | Baseline | 85 |
| 2 | 4/20/2015 | Baseline | 78 |
| 3 | 4/27/2015 | Baseline | 86 |
| 4 | 5/4/2015 | Baseline | 81 |
| 5 | 5/11/2015 | Baseline | 82 |
| 6 | 5/18/2015 | Baseline | 88 |
| 7 | 5/25/2015 | Baseline | 83 |
| 8 | 6/1/2015 | Baseline | 86 |
| 9 | 6/8/2015 | Baseline | 85 |
| 10 | 6/15/2015 | Baseline | 88 |
| 11 | 6/22/2015 | Baseline | 82 |
| 12 | 6/29/2015 | Baseline | 78 |
| 13 | 7/6/2015 | During Project | 81 |
| 14 | 7/13/2015 | During Project | 85 |
| 15 | 7/20/2015 | During Project | 83 |
| 16 | 7/27/2015 | During Project | 88 |
| 17 | 8/3/2015 | During Project | 86 |
| 18 | 8/10/2015 | During Project | 89 |
| 19 | 8/17/2015 | During Project | 87 |
| 20 | 8/24/2015 | During Project | 85 |
| 21 | 8/31/2015 | During Project | 90 |
| 22 | 9/7/2015 | During Project | 89 |
| 23 | 9/14/2015 | During Project | 92 |
| 24 | 9/21/2015 | During Project | 90 |
| 25 | 9/28/2015 | During Project | 93 |
| 26 | 10/5/2015 | During Project | 89 |
| 27 | 10/12/2015 | Post Project | 94 |
| 28 | 10/19/2015 | Post Project | 97 |
| 29 | 10/26/2015 | Post Project | 96 |
| 30 | 11/2/2015 | Post Project | 91 |
| 31 | 11/9/2015 | Post Project | 97 |
| 32 | 11/16/2015 | Post Project | 98 |
| 33 | 11/23/2015 | Post Project | 99 |
| 34 | 11/30/2015 | Post Project | 94 |
| 35 | 12/7/2015 | Post Project | 95 |
| 36 | 12/14/2015 | Post Project | 97 |
| 37 | 12/21/2015 | Post Project | 97 |
| 38 | 12/28/2015 | Post Project | 96 |
| 39 | 1/4/2016 | Post Project | 97 |
Solution
Question 6
The operational data at a pizza processing facility in upstate New York are as follows:
One workday = 8 hours
Lunch time =30 min
Break (twice per shift) = 15 min each
Number of shifts = 2
Days per week = 5
Demand = 300 units per week
Total waiting time per unit = 75 min per unit
Delay from other activities = 30 min per unit
Compute the following:
Solution