Question

For a process, the average range for all samples was 5 and the process average was 25. If the sample size was 10, calculate UCL for the R-chart.

Answer 1

8.885

Explanation:

Given that :

Sample size, n = 10

The average range, Rbar for all samples = 5

The upper control limit, UCL for the R-chart is :

UCL L= D4Rbar

From the control chart constant table, D4 = 1.777

Hence,

UCL = 1.777 * 5

UCL = 8.885

The UCL for the R-chart is 8.885