I have two questions that I just can't figure out correctly.

1. If x-bar is 4.725 and R-bar is 0.0096, and n=4, then the UCL sub R and LCL sub R are?
A. 0 and 0.022
B. 0.022 and 0
C. 0.563 and 0.563
D. 0.022 and 1.00

2 If x-bar is 4.725 and R-bar is 0.0096, and n=4, then the UCL sub x-bar and LCL sub x-bar are:
A. 4.732 and 2.718
B. 2.345 and 4.718
C. 4.732 and 4.718
D. Cannot be answered with the data

I keep trying the formulas but my answers do not match the given.. any help ?

Thanks

Quote:

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Originally Posted by ken1014

I have two questions that I just can't figure out correctly.

1. If x-bar is 4.725 and R-bar is 0.0096, and n=4, then the UCL sub R and LCL sub R are?
A. 0 and 0.022
B. 0.022 and 0
C. 0.563 and 0.563
D. 0.022 and 1.00

2 If x-bar is 4.725 and R-bar is 0.0096, and n=4, then the UCL sub x-bar and LCL sub x-bar are:
A. 4.732 and 2.718
B. 2.345 and 4.718
C. 4.732 and 4.718
D. Cannot be answered with the data

I keep trying the formulas but my answers do not match the given.. any help ?

Thanks

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Please explain your notation. What is R? Does UCL and LCL stand for upper and lower class limits?

I've found this page which has some info:
The Control Chart

x-bar is average of x values, R is range of x values (max x - min x) and R-bar is average of Rs. UCL is Upper Control Limit and LCL is Lower Control Limit.
I assume that UCL sub R is Upper Control Limit for the range.

I'm not familiar enough with this field to really offer a good answer. Maybe if ken1014 gives us the equations he's using we can see if he's made math errors at least.