Consider again that the company making tires for bikes
is concerned about the exact width of its cyclocross tires. The
company has a lower specification limit of 22.8 mm and an upper
specification limit of 23.2 mm. The standard deviation is 0.15 mm
and the mean is 23 mm. The company now wants to reduce its defect
probability as 0.01. To what level would it have to reduce the
standard deviation in the process to meet this
target?
Process is centered and for 99% probability of producing good items,
z should be 2.58 for each side of defects which should be less than 0.005 of total items
Hence 2.58 = USL -Mean / SD
which means that SD = 23.2-23 / 2.58 = 0.07751
Consider again that the company making tires for bikes is concerned about the exact width of its cyclocross tires