Over a Twenty Hour Period Forty Samples of Five Items $\bar { \bar { X } }$

Multiple Choice

Over a twenty hour period forty samples of five items each were collected.From this data, the values calculated for $\bar { \bar { X } }$ and $\bar { R }$ were 120.10 and 45.75 respectively.Based on this data, the upper control limit for the X bar control chart should be set at
Approximately:

A) 120.10
B) 129.43
C) 146.49
D) 165.85