Exam 15: Statistical Quality Control

If we are attempting to control the diameter of bowling balls, we will find a p-chart to be quite helpful.

Control charts that are used to monitor processes that are measured in continuous units are classified as which of the following?

Table 15-1 -Refer to Table 15-1.Bags of tea are sampled to ensure proper weight.The overall average for the samples is 8 ounces.Each sample contains 10 bags.The average range is 0.1 ounces.What is the lower limit of the sample averages chart?

A p-chart has been developed for a particular item.In the past, 4% of such items have been found to be defective.If a sample of 100 is taken, and 9 of these are found to be defective, should the process be considered out of control based on 99.7% control limits? Explain.

The p-chart would be useful when we

The independent axis of a control chart is time.

A company has been receiving complaints about the attitude of some sales clerks.Over a 10-day period, the total number of complaints was 250.The company wishes to develop a control chart for the number of complaints.What would the upper control limit on the number of complaints per day be for a 2 sigma (95.5%)control chart?

A professor gives a series of twenty quizzes in his operations planning and control class just to keep his students on their toes.Each quiz consists of one hundred true-false questions and the results for one student are shown in the table.Construct an appropriate control chart for this situation.Is the student in control?

All that is required to develop limits for a C-chart is knowledge of the average count of defects.

Variations that need not occur in production processes are referred to as

A plant manager is concerned with the variability of beer being filled in 12 oz.cans.The most appropriate control chart would be which of the following?

The central limit theorem states that the distribution of x-bars will tend to follow a normal distribution as long as the population they are drawn from is normally distributed.

A company believes a process monitored by an x-bar chart to be in control.When the most recent control point exceeded the UCL value by 20%, the company should

The standard deviation of a process can be described as

Assignable variations in a process are also called natural variations.

Bags of pretzels are sampled to ensure proper weight.The overall average for the samples is 9 ounces.Each sample contains 25 bags.The standard deviation is estimated to be 3 ounces.The upper control chart limit (for 99.7% confidence)for the average would be ________ ounces.