For a manufacturing process, $\overline { \overline X }$
= 10 inches, $\overline { \mathrm { R } }$
= )4 inches,and the subgroup sample size is 6 units.Calculate the standard control limits for the R chart.
A)0 and .846
B)0 and .802
C)0 and .77
D)0 and 1.0
E)-.09 and .89

Question

For a manufacturing process, $\overline { \overline  X }$ 
= 10 inches, $\overline { \mathrm { R } }$
= )4 inches,and the subgroup sample size is 6 units.Calculate the standard control limits for the R chart.
A)0 and .846
B)0 and .802
C)0 and .77
D)0 and 1.0
E)-.09 and .89

Quizplus · Accepted Answer

The upper control limit (UCL) for the R chart is given by:
UCL = $\overline { \mathrm { R } }$ + (A2 * $\overline { \overline  X }$)
where A2 is a constant based on the subgroup size, n=6 in this case. According to the R chart constants table, A2 = 0.577. Therefore,
UCL = 4 + (0.577 * 10) = 9.77 inches
The lower control limit (LCL) for the R chart is always 0. Therefore, the standard control limits for the R chart are 0 and 0.802. The correct answer is B.

For a Manufacturing Process X‾‾\overline { \overline X }X = 10 Inches

For a Manufacturing Process $\overline { \overline X }$ = 10 Inches