Use the Information Below to Answer the Following Question(s)

Multiple Choice

Use the information below to answer the following question(s) .Use the "Factors for Control Limits" Table A.3 from the textbook where required:
A control chart needs to be developed to determine if the temperature for a process is within control limits.Five samples each having 4 observations are taken and the sample measurements (temperature in degrees F) are noted in the table below:

-What is the value of the average range R-bar?

A) 3.68
B) 8.398
C) 3.125
D) 5.252