Question

Consider Chapter? 3, Problem 4 that was a homework problem dealing with the quality of Aspen Plastics bottle neck diameters. For randomly entered? data, results were obtained as shown? below:

For the data? shown, the calculation of the Lower Control Limit for the? X-bar chart is equal to which of the? following?

A. none of these

B. =D9-D10*D16

C. =D9+D10*D16

D. = 0.729

PLEASE INDICATE CORRECT ANSWER ONLY!

Solver -R and X-Bar Charts 5 Enter data in yellow shaded areas Enter Manually alculate from the sample data 9 10 Average Range 11 Sample Size 12 0.5991 0.0355 4 14 LCL Factor, R 15 UCL Factor, R 16 CL Factor, X-bar 17 LCL, R chart UCL, R chart LCL, X-bar chart UCL, X-bar chart 0.0000 0.0810 0.5732 0.6250 2.282 0.729

Answer 1

Lower Control Limit for X bar chart

= Xbar – A2 x Rbar

Where,

Xbar = Average value of sample means

A2 = Value of constant as derived from standard table for Xbar and Range chart

Rbar = Average range

In the given case ,

D16 stands for value of A2 ( i.e. control Limit factor for Xbar )

D10 stands for Rbar average range

We would have accepted CLCL of Xbar chart as :    

D9 – D10 X D16

Provided D9 stood for Xbar

However it is mentioned that D9 is the “target value” and not “Xbar”

Therefore , answer would be “A.None of the Above “