Read the case given below and answer the questions given at the end.
CASE STUDY – I
ABC Company Ltd, a manufacturer of floppy disks, inspects a sample of 50 disks from each day's output. A quality inspector of the company decides on the acceptability or otherwise of the disks based on a variety of attributes.
Date No of Defectives Date No of Defectives Date No of Defectives
18.02.2010 3 25.02.2010 7 03.03.2010 7
19.02.2010 10 26.02.2010 18 04.03.2010 6
20.02.2010 13 27.02.2010 1 05.03.2010 19
21.02.2010 4 28.02.2010 0 06.03.2010 3
22.02.2010 12 29.02.2010 4 07.03.2010 9
23.02.2010 14 01.03.2010 9 08.03.2010 7
24.02.2010 08 02.03.2010 22
defectives in the sample over the past 20 days are given above.
The production manager suspects that the variation in quality was due to deputing an inexperienced substitute operator instead of a regular one, on three days during the period. With the use of a fraction defective chart, specifying the upper and lower control Limits or otherwise, determine the days of poor quality which can be traced or assigned to the inexperienced operator. Do the number of such days, match the number of points indicating out of control situations