A Machine Produces Drive Shafts

Multiple Choice

A machine produces drive shafts. Manufacturing currently takes samples of 10 shafts every half an hour to check if the process is in control. Control limits have been set at ± 3 standard deviations of the sample means and are set at 10 ± 3×0.001 cm. A suggestion calls for control limits to be tightened to ± 2 standard deviations, i.e., 10± 2×0.001 cm. As a result the proportion of shafts produced that are defective (outside specification limits) will

A) Increase
B) Decrease
C) Remain unchanged