# Statistical Quality Control (ISS (Statistical Services) Statistics Paper IV): Questions 21 - 23 of 34

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## Question number: 21

» Statistical Quality Control » Control Charts » Attributes

Essay Question▾

### Describe in Detail

The following are the figures of defectives in 22 lots each containing 2, 000 bulbs. Ind control limit for p-Chart.

 425 430 216 341 225 322 280 306 337 305 356 402 216 264 126 409 193 326 280 389 451 420

### Explanation

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## Question number: 22

» Statistical Quality Control » Control Charts » Attributes

Essay Question▾

### Describe in Detail

Each day a sample of 1500 items from a production process was examined. The number of defectives found in each sample was as follows. With a suitable control chart, check out for control 4, 6, 6, 2, 15, 4, 4

### Explanation

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## Question number: 23

» Statistical Quality Control » Control Charts » Variable

Essay Question▾

### Describe in Detail

a) The number of customer complaints are recorded at a television manufacturing company. Complaints have been recorded over the past 20 weeks. Construct 3-σ control limits for the c-chart.

 Week No. of complaints Week No. of complaints 1 0 11 4 2 3 12 3 3 4 13 1 4 1 14 1 5 0 15 1 6 0 16 0 7 3 17 2 8 1 18 1 9 1 19 2 10 0 20 2

b) A machine is manufacturing mica discs. samples of size 5 are drawn every hour and their thickness in units are recorded as follows. From this data construct 3-σ control limits for chart.

 Sample No. Observstions 1 8 9 15 4 11 2 7 10 7 6 8 3 11 12 10 9 10 4 12 8 6 9 12 5 11 10 6 14 11 6 7 7 10 4 11 7 10 7 4 10 10 8 8 11 11 7 7 9 8 11 8 14 12 10 12 9 12 17 11 11 7 7 9 17 13 12 9 9 4 4 11 13 10 12 12 12 12 14 8 11 9 6 8 15 10 13 9 4 9 16 9 11 8 5 11

### Explanation

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