Exam 12: Statistically Based Quality Improvement for Attributes

Fifty defibrillators are tested for 48 hours per machine. Of all the machines tested, 2 experience malfunctions during the test. What is the failure rate for the machines?

The p chart is a process chart that is used to graph the proportion of items in a sample that are defective.

One way to raise system availability would be to lower the mean time to repair.

Defectives are monitored using ________.

Two components of reliability 0.95 are in parallel and this subsystem is connected in series to a component with a reliability of 0.95. The overall system reliability is ________.

A producer of contact lenses regularly takes samples of 100 lenses and inspects them for scratches. If a lens has a single scratch, it cannot be sold. The results of 10 samples are shown. What are the lower and upper 3-sigma control limits?

The vertical axis on the bathtub curve is failure rate.

The reliability model that shows that products are more likely to fail either very early in their useful life or very late in their useful life is called the ________.

The u chart is a graph of the number of defects per unit.

A parks and recreation worker counts the number of paint drips on each standard size park bench. The results from the last 10 benches are shown. If the Parks Department decides to make a c chart, what should the lower and upper 3-sigma control limits be?

Describe the differences between a defect and a defective. Provide an example of each and identify the types of process charts that would monitor defects and defectives.

Two components of reliability 0.90 are in parallel and this subsystem is connected in series to a component with a reliability of 0.95. The overall system reliability is ________.

A system is composed of three components in series having reliabilities of 0.99, 0.98, and 0.97. What is the overall system reliability?

When testing failure rate, there is no distinction as to whether hours of testing are continuous or performed at separate times.

One way to achieve very high system availability would be for the mean time between failures to be as low as possible.

A quality engineer notes that a process produces data that are binomial and has been obtained using a sample space that is constant. The primary interest of the process manager is in the percentage of bad parts. An appropriate control chart to use would be a(n)________.

Which of the following is an example of a statistic based on an attribute?

Reliability models assume independence between failure events.

A system has an availability of 90% and a mean time to repair of 48 hours. What is the mean time between failures?

The producers of the Yugo automobile periodically inspect samples of 80 hoods for dents and scratches. A single flaw in a hood renders it unsuitable for installation in one of their fine automobiles. The results of the last 10 samples are shown. Calculate the standard error, snp, for the np chart.