The process is in control or not.
Answer to Problem 4.71P
The range is not within the control limits; therefore the process is not in control.
Explanation of Solution
Given:
The sample size is,
The average of averages of sample size is,
The average range is,
The standard deviation is,
Formula used:
The formula for the upper control limit for the averages is given as,
Here,
The formula for the lower control limit for the averages is given as,
The formula for the upper control limit for the ranges is given as,
Here,
The formula for the lower control limit for the ranges is given as,
Here,
Calculation:
Refer to the Table 4.2 to obtain the value of “Constants for control charts” for the sample size of 7.
The values of constants are given as,
The value of the upper control limit for the averages can be calculated as,
The value of the lower control limit for the averages can be calculated as,
The value for the upper control limit for the ranges can be calculated as,
The value for the lower control limit for the ranges can be calculated as,
The value of average for the given sample can be calculated as,
The value of range for the given sample can be calculated as,
The average is within the limit as,
But the range is not within the upper and lower limit as,
Conclusion:
Thus, the range is not in control limits, therefore the process is not in control.
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Chapter 4 Solutions
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