Question

A 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 specifica- tion limit of 23.2 mm. The standard deviation is 0.15 mm and the mean is 23 mm. What is the process capability index for the process?

Answer 1

Answer:

Capability index = 0.4444

Explanation:

Given:

lower specification limit = 22.8 mm

Upper specification limit = 23.2 mm

The standard deviation = 0.15 mm

Mean = 23 mm

Capability index = ?

Computation of Capability index:

Capability index = minimum of [ $\frac{USL-mean}{3(SD)} ,\frac{mean - LSL}{3(SD)}$ ]

Capability index = minimum of [  $\frac{23.2-23}{3(0.15)} ,\frac{23 - 22.8}{3(0.15)}$ ]

Capability index = minimum of [  $\frac{0.2}{0.45} ,\frac{0.2}{0.45}$ ]

Capability index = minimum of [  $0.4444 , 0.4444$ ]

Capability index = 0.4444