A manufacturer of hair oil has an automated
process consisting of a filling machine for filling the 200-ml bottles and a
sealing unit. After filling the bottle, it is automatically sealed with a
metallic cap. To monitor the quality of the process, samples of size 5 are
drawn periodically from the process and the quantity filled is measured. Table
19.12 has data on 12 such observations.
Construct a variable control chart and
investigate if the process is in control.