Statistical Quality Control-Control Charts (ISS Statistics Paper IV): Questions 6 - 8 of 31

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Question number: 6

» 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. Obtain the 3-σ control limits for the p chart.

Given are observations find control limits for the P - Chart

Given are observations find control limits 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 pi=pi2000(i=1,2,,22)

Given are observations Correct control limits for P Chart

Given are observations control limits for P Chart

S. No.

d

pi=pi2000

1

425… (189 more words) …

Question number: 7

» Statistical Quality Control » Control Charts » Variable

Essay Question▾

Describe in Detail

A electric Company uses a process to paint cars with a coat of enamel. During each shift, a sample of five cars is selected and the thickness of the paint in mm is determined. On the basis of X¯ and R charts, Check whether the production is under control?

Check whether production is under control

Find if production is under control

Sample No.

Observations

1

2.6

2.3

2.6

2.7

2.7

2

2.6

2.6

2.4

2.8

2.3

3

2.4

2.3

2.4

2.5

2.3

4

2.7

2.4

2.3

2.6

2.8

5

2.6

2.6

2.5

2.8

2.1

6

2.2

2.2

2.7

2.3

2.6

7

2.0

2.6

2.4

2.2

2.3

8

2.5

2.6

2.6

2.7

2.8

9

2.4

2.4

2.2

2.8

2.3

10

2.6

2.3

2.0

2.5

2.4

11

3.1

3.0

3.5

2.8

3.0

12

2.4

2.8

2.2

2.9

2.5

13

2.1

3.2

2.5

2.6

2.8

14

2.2

2.8

2.1

2.2

2.4

15

2.4

3.0

2.5

2.5

2.0

16

3.1

2.6

2.6

2.8

2.1

17

2.9

2.4

2.9

1.3

1.8

18

1.9

1.6

2.6

3.3

3.3

19

2.3

2.6

2.7

2.8

3.2

20

2.0

2.8

2.3

1.8

2.9

Explanation

Check whether production is under control Total, mean and range

Find if production is under control

Sample No.

Observations

Total

Sample Mean ( X¯)

Sample Range (R)

1

2.6

2.3

2.6

2.7

2.7

12.70

2.54

0.40

2

2.6

2.6

2.4

2.8

2.3

12.70

2.54

0.50

3

2.4

2.3… (401 more words) …

Question number: 8

» Statistical Quality Control » Control Charts » Variable

Essay Question▾

Describe in Detail

Six samples, which contain 20 observations per sample, have been collected and the sample means and sample ranges are computed as shown below. Test whether the sample means are within control limits for X¯chart ?

Test mean samples and check if they are in control limits

Test mean samples and check if they are in control limits

Sample

Mean

Range

1

3.06

0.42

2

3.15

0.5

3

3.11

0.41

4

3.13

0.46

5

3.06

0.46

6

3.09

0.45

Explanation

The sample size here is 20.

We are given that

Calculating mean and range to test mean samples and check if they are in control limits

Test mean samples and check if they are in control limits Mean and range

Sample

Mean ( X¯i)

Range (R)

1… (160 more words) …

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