PMI Quality Planning & Control Charts 4

Question 1

A process capability index (Cp) of 1.33 indicates that:

Accepted Answer

The process spread fits within the specification limits with a safety margin

Answer

A Cp of 1.33 means the process spread (6σ) occupies only 75% of the specification width, providing a reasonable safety margin — it is considered a minimum acceptable capability level.

Question 2

What distinguishes Cpk from Cp in process capability analysis?

Accepted Answer

Cpk accounts for process mean centering; Cp assumes the mean is perfectly centered

Answer

Cpk measures how close the process mean is to the nearest specification limit, penalizing off-center processes that Cp would rate as capable.

Question 3

In a fishbone (Ishikawa) diagram used for quality planning, the 'bones' branching off the spine typically represent:

Accepted Answer

Major categories of potential causes of a quality problem

Answer

The branches of a fishbone diagram represent major cause categories (e.g., Man, Machine, Method, Material, Measurement, Environment) from which specific causes are brainstormed.

Question 4

Which type of control chart would be MOST appropriate for monitoring the number of blemishes found per car in an automotive paint inspection where every car is inspected?

Accepted Answer

c-chart

Answer

A c-chart is used when counting defects per unit with a constant inspection unit (each car), following the Poisson distribution.

Question 5

A project quality plan states the process must operate within ±2σ of the mean. What percentage of output would theoretically fall within these limits for a normal distribution?

Accepted Answer

95.45%

Answer

For a normal distribution, ±2 standard deviations from the mean encompasses approximately 95.45% of all values.

(PMI) Project Management Institute Certified Practice Test

(PMI) Project Management Institute Certified Practice Test

PMI Quality Planning & Control Charts 4