Two types of control charts are being used to monitor the tensile strength (in kgs/cm2) of steel beams produced by Steel America, Inc. Currently the process is statistically in control, with µ=250 and σ=5
Two options are being used simultaneously to control the process
Option 1: x-bar & R chart with n=7 every 30 minutes
Option 2: x-bar & s chart with n=14 every hour
If the mean of the process changes to a new value of µ’=257 due to the presence of special causes of variation, how long it would take -in hours- for each option to detect the change?