For a manufacturing process, = 10 inches, = .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,  = 10 inches,  = .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

To calculate the standard control limits for the R chart, use the formula:
Upper Control Limit (UCL) = D4 * R bar
Lower Control Limit (LCL) = D3 * R bar
where D3 and D4 are constants that depend on the subgroup sample size. For a subgroup sample size of 6, D3 = 0 and D4 = 2.575. 
Therefore, UCL = 2.575 * 0.4 = 1.03 and LCL = 0, giving standard control limits of 0 and 1.03. However, since an R value of 0 is not possible, the lower control limit is effectively 0. Therefore, the answer is B, with a lower control limit of 0 and an upper control limit of 1.03.

For a Manufacturing Process, = 10 Inches, =