# Changing process average in control charts

#### Clarkson

##### New Member
Data is given for a X bar and R chart of subgroup size=4.
.

The control limits are
for X bar chart:
center line=178.46
UCL=184.1146
LCL=172.8054

for R chart:
center line=8.3888
UCL=17.734
LCL=0
In this question I don't understand to do the following part :
.