Refer to Table S6.1 - Factors for Computing Control Chart Limits (3 sigma)

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Sample

Size, n

Mean Factor,

A2

Upper Range,

D4

Lower Range,

D3

2

1.880

3.268

0

3

1.023

2.574

0

4

0.729

2.282

0

5

0.577

2.115

0

6

0.483

2.004

0

7

0.419

1.924

0.076

8

0.373

1.864

0.136

9

0.337

1.816

0.184

10

0.308

1.777

0.223

12

0.266

1.716

0.284

for this problem.

Auto pistons at Wemming Chung's plant in Shanghai are produced in a forgingprocess, and the diameter is a critical factor that must be controlled. From sample sizes of

10

pistons produced each day, the mean and the range of this diameter have been as follows:

Day	Mean x (mm)	Range R (mm)
1	156.9	4.0
2	155.2	4.8
3	153.6	4.3
4	155.5	4.8
5	158.6	4.3

a) What is the value of

x?

x=nothing

mm (round your response to two decimal places).