Table $7.1$ Factors for Calculating Three- Sigma Limits for The $\overline { \bar { X } }$

Table $7.1$
Factors for Calculating Three- Sigma Limits for the $\overline { \bar { X } }$ - chart and $R$ - chart


-A milling operation has historically produced an average thickness of 0.005 inch with an average range of 0.015 inch. Currently, the first three items from each batch of 20 are inspected. Use Table 7.1 What is the value of the $$L C L \bar { X } ?$$

A) less than or equal to 0.00100
B) greater than 0.00100 but less than or equal to 0.00299
C) greater than 0.00299 but less than or equal to 0.00499
D) greater than 0.00499