LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034
B.Sc. DEGREE EXAMINATION – STATISTICS
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SIXTH SEMESTER – APRIL 2008
ST 6602 – STATISTICAL PROCESS CONTROL
Date : 23/04/2008 Dept. No. Max. : 100 Marks
Time : 9:00 – 12:00
PART – A
Answer ALL the questions: (10 x 2 = 20)
- Mention the reasons for Quality improvement in a new business strategy.
- What is TQM philosophy?
- What is the Box plot?
- Explain the Stem and Leaf plot.
- Define Statistical Process control.
- What benefits are expected out of the use of control charts?
- What is a CUSUM chart?
- Define process capability analysis and mention its purpose.
- Mention disadvantages of Acceptance sampling.
- What is item – by – item sequential sampling plan?
PART – B
Answer any FIVE questions. (5 x 8 = 40)
- Explain how variation is described through the frequency distribution and histogram.
- Explain the link between Quality improvement and productivity.
- How will you prepare the control charts for fraction defectives?
- Distinguish between CUSUM chart and Shewhart chart.
- Discuss the process capability analysis using a control chart.
- How can the Shewhart control charts be interpreted to draw meaningful conclusions?
- What is acceptance sampling? Mention the situations it is most likely to be useful.
- Describe the operating procedure of double sampling plan.
PART – C
Answer any TWO questions. (2 x 20 = 40)
- a) State the specific functional responsibilities of total Quality Management.
- b) A TV voltage stabilizer manufacturer checks the quality of 50 units of his product nonconforming units are as follows.
Days: | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |
Fraction defectives: | 0.10 | 0.20 | 0.06 | 0.04 | 0.16 | 0.02 | 0.08 | 0.06 | 0.02 |
Days: | 10 | 11 | 12 | 13 | 14 | 15 |
Fraction defectives: | 0.16 | 0.12 | 0.14 | 0.08 | 0.10 | 0.06 |
Construct 3 – sigma trial Control limits for fraction defectives and comment on it.
(12+8)
- a) How do you set the Control limits for R-charts in Statistical quality control?
- b) Sixteen boxes of electric switches each containing 20 switches were randomly selected from a lot of switch boxes and inspected for the number of defects per box. The numbers of defects per box were as follows:
Box Numebr: | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |
No. of defects: | 12 | 15 | 9 | 14 | 18 | 26 | 8 | 6 | 11 | 12 |
Box Number: | 11 | 12 | 13 | 14 | 15 | 16 |
No. of defects: | 16 | 13 | 19 | 18 | 14 | 21 |
Calculate 3-sigma limits for c-chart and draw conclusion. (12+8)
- a) Describe the operational aspects of CUSUM charts and the role of v-mask.
- b) How can sequential sampling plan be implemented graphically under SPRT? (12+8)
- a) Explain the Operating procedure of Single Sampling plan and obtain its OC curve.
- b) What are continuous sampling plans and mention a few situations where these plans are applied. (12+8)
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