We wish to determine if screw production is in statistical control. We have no prior info, other than the 5 samples(each sample has 4 observations)

Number 1 2 3 4

Sample 1 0.5014 0.5022 0.5009 0.5027

sample 2 0.5021 0.5041 0.5032 0.5020

sample 3 0.5018 0.5026 0.5035 0.5023

sample 4 0.5008 0.5034 0.5024 0.5015

sample 5 0.5041 0.5056 0.5034 0.5039

1. Compute the sample range and mean each of the 5 samples.

2. Compute x, the average of the sample means, and R, the average of the sample ranges.

3. Construct the X chart to check if the sample mean is in control.

4. Construct the Range chart to check if process variation is in control.