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Which control chart must have at least 20 subgroups of observed values to judge whether a process is in control or not?

OPTIONS

R-Chart
C-Chart
P-Chart
Y-Chart

ANSWER

R-Chart

EXPLANATION

An R-Chart must have at least 20 subgroups of observed values to judge whether a process is in control or not.

«Process capability (Cp) describes a process often in a stable manufacturing environment that leads to the production of a product that conforms to client and design specifications. An ideal process will have a Cp value of:

Given an average of 1.84 defects per 5 units, what is the upper limit of the control chart to be set?»