# ISS Statistics Paper IV: Questions 28 - 30 of 79

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## Question number: 28

» 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

We have n = 2000

 S. No. d Equation 1 425 0.2125 2 430 0.215 3 216 0.108 4 341 0.1705 5 225 0.1125 6 322 0.161 7… (105 more words) …

## Question number: 29

» 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

We have n = 30

 S. No. d Equation 1 4 0.00267 2 6 0.00400 3 6 0.00400 4 2 0.00133 5 15 0.01000 6 4 0.00267… (61 more words) …

## Question number: 30

» 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

a) Average number of defects per sample is

=1.5+ =1.5 + 3 (1.22) =5.174

= →0

Since number of defects cannot be negative, can be considered as zero. (rounded up to zero)

b) Second question:

Construct 3 sigma control limit for x bar-chart… (194 more words) …

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