LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

B.Sc. DEGREE EXAMINATION – STATISTICS

SIXTH SEMESTER – APRIL 2011

ST 6605/ST 6602 – STATISTICAL PROCESS CONTROL

 

 

 

Date : 09-04-2011              Dept. No.                                                    Max. : 100 Marks

Time : 9:00 – 12:00

 

SECTION   A (10 x 2 = 20 Marks )

Answer ALL the questions

1. What do you mean by the term “ cost of quality” ?
2. List the characteristics of TQM derived from its definitions.
3. When do you use Histogram ?
4. What do you mean by frequency distribution ?
5. Mention the purpose of the p-chart.
6. When are C- charts used ?
7. What are control charts ?
8. The following are the and R values of  4 sub-groups of readings:

= 10.2 , 12.1, 10.8 and 10.9

R  =  1.1 ,  1.3  , 0.9 and 0.8

A₂= 0.73 ; D₃ = 0 ; D₄ = 2.28  ; d₂ = 2.059

Find the control limits for   chart.

9. What does average total inspection mean?
10. Define Consumer’s Risk and Producer’s Risk.

 

SECTION B  ( 5 x 8 = 40 Marks )

Answer any FIVE questions

11. Explain “Cost of Prevention”.
12. State the benefits of TQM
13. Explain the Box Plot technique.
14. Explain the logic behind the usage of 3 sigma control limits.
15. What are the advantages of variable control charts over attribute control charts?
16. Distinguish between CUSUM chart and Shewhart  control chart.
17. What do you mean by Acceptance sampling ? Mention the situations it is most likely to be useful
18. Explain the OC curve for a single sampling plan.

SECTION   C ( 2 x 20 = 40 Marks )

Answer any TWO questions

1. a) State the requirements for successful implementation of TQM

 

1. b) The following are weekly yield data from a semiconductor fabrication facility.  Construct a

Stem and Leaf-plot  by selecting the stem values 5, 6,7,8 and 9.

 

Week :  1     2      3      4      5     6      7     8   9    10   11   12   13   14     15    16    17    18    19   20

Yield   : 58   63   69   72    51   79   83   86   85   78   87   83   64   73     81    68    72    65    91   88

Week:  21     22    23   24   25    26  27   28   29   30   31   32    33    34   35   36    37   38     39    40

Yield   : 64    68    67   60   59    63   64  52   70   92   75   76    81    74   82    76   75    62    63    92

 

 

20. a) What are p and np charts? How they are constructed?
21. b) Discuss in detail the criteria for lack of control with respect to  -chart.

 

21. a) Describe the operational aspects of CUSUM charts and the role of V-mask.
22. b)  A certain product has been statistically controlled at a process average of 46 and a standard

deviation of 1.00. The product is presently being sold to two customers who have different

specification requirements.  Customer A has established a specification of 48 4.0 for the

product, and customer B has specification of 46  4.0. Use normal distribution and find what

percentage of items go outside the specification limits of (i) Customer A, (ii) Customer B.

 

22. a) Mention the advantages and disadvantages of Acceptance Sampling.
23. b) Explain Double Sampling Plan in detail.

 

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