According to the specifications that a customer gave to a manufacturer, the length of a shoe should not deviate from the correct size by more than 1 mm. In the manufacturing process, the standard deviation of this length is 0.32 mm, and the mean is equal to the correct size. What is the capability ratio of this process for three standard deviations, and is this process capable

Capability ratio = 1.04166

Explanation:

Given:

Length of a shoe (not deviate) = 1 mm

Standard deviation of this length = 0.32 mm

Number of standard deviations = 3

Find:

Capability ratio = ?

Computation:

Capability ratio = [Length of a shoe (not deviate) / Standard deviation of this length] / Number of standard deviations

Capability ratio = [1 / 0.32] / 3

Capability ratio = 3.125 / 3

Capability ratio = 1.04166

Capability ratio is greater than 1, therefore process is capable.