Question

A telephone customer service center wants to ensure that the majority of its customers’ calls are answered within a reasonable amount of wait time. Based on customer surveys, the company determined that the acceptable wait time that customers considered acceptable is between 10 and 45 seconds. A large sample of current customer calls was monitored. The average wait time was found to be 31 seconds with a standard deviation of 4.5 seconds.
What is the Capability Index for this process?

A. 1.30
B. 1.04
C. 1.56
D. 0.43

Answer 1

Answer:

The Capability Index for this process is 1.04. The right answer is B

Explanation:

According to the given data we have the following:

μ = 31 Seconds

USL = 45

LSL = 10

Standard deviation σ= 4.5

Therefore, in order to calculate the Capability Index for this process we would have to use the following formula:

Cpk=Min( USL-μ  ,  μ- LSL)

               3×σ            3×σ

Cpk=Min( 45-31  ,  31- 10)

               3×4.5      3×4.5

Cpk = Min ( 1.04,1.56) = 1.04

The Capability Index for this process is 1.04