Sarah Soliz,Director of Quality Programs,is designing and R charts for the rod shearing process at Stockton Steel.She has 26 samples of rod length,and each sample included measurements of 5 rods.The mean of the 26 sample means is 112 inches,and mean of the 26 ranges is 0.15 inch.The upper control limit for her R chart is ____.
A)0.150
B)10.57
C)0.317
D)2.114
E)0.713

Question

Sarah Soliz,Director of Quality Programs,is designing  and R charts for the rod shearing process at Stockton Steel.She has 26 samples of rod length,and each sample included measurements of 5 rods.The mean of the 26 sample means is 112 inches,and mean of the 26 ranges is 0.15 inch.The upper control limit for her R chart is ____.
A)0.150 
B)10.57 
C)0.317 
D)2.114 
E)0.713

Quizplus · Accepted Answer

The upper control limit for the R chart is calculated by:
UCL(R) = D4*R_bar
where D4 = 2.115 for sample size 5, and R_bar = average range = 0.15. Therefore, UCL(R) = 2.115*0.15 = 0.317. Therefore, the correct answer is (C) 0.317.

Sarah Soliz,Director of Quality Programs,is Designing and R Charts