Exam 17: Statistics for Quality: Control and Capability

At the start of the semester,a professor wants to monitor students who miss class.The professor implements a new attendance policy geared toward encouraging students to attend class every day.There are currently 150 registered students in the class,and each day the class takes a quiz that is just used to measure attendance.The number of quizzes that are turned in will serve as the measure of attendance.The quizzes are given at every class period and the class meets four times per week over a 15-week semester.What is the value of the UCL?

Under what circumstances will the process capability indexes and be equal?

The data below represent the means from 15 sample control charts for the amount of time in minutes it takes students to complete a quiz in a basic statistics course.The same quiz was given to 15 different sections of a basic statistics course.Five students were sampled from each class and each mean is shown below. What is the value of the lower control limit?

The _______ the value of C_p or C_pk,the more _____ the process.

Which of the following is true about s and R charts?

An important characteristic in the proper operation of ignition keys for automobiles is the groove width of the key.In a large manufacturing plant that produces thousands of keys,control charts have been established to monitor the process of cutting the groove.It is believed that the measurement (in inches)of the groove width is Normally distributed.Over a period of time,20 samples,each of size n = 5,were selected in order to establish 3-sigma and s charts.From these samples the following were determined: = 0.15932 and = 0.0193438.What is the value of the center line on the chart and on the s chart,respectively?

Suppose we use a "run of eight" rule;that is,we declare the process out of control if eight consecutive points are all above the center line of the chart or if eight consecutive points are all below the center line of the Chart.If the process is in statistical control,what is the (approximate)probability that we declare the process out of control using this rule?

Piston rings for an automotive engine are produced by a forging process.We wish to monitor the inside diameter of the rings manufactured by this process using an and an s control chart.Samples of size 4 are to be taken at regular intervals,and the sample means and standard deviations are computed and plotted on the charts in time order.The target values for the inside diameter are a mean of  = 75 millimeters and a standard deviation of  = 0.02 millimeters.The control chart constants are (partially)reproduced below. What is the upper control limit for the Chart?

In an electronics company that produces transistors,1000 transistors are inspected at regular intervals.The proportion of nonconforming transistors produced by the process,estimated from data collected in a 1-month period,is = 0.0026.What would be the value of the lower control limit for a p chart of future samples of size 10,000?

The data below represent the means from 15 sample control charts for the amount of time in minutes it takes students to complete a quiz in a basic statistics course.The same quiz was given to 15 different sections of a basic statistics course.Five students were sampled from each class and each mean is shown below. What is the value of the upper control limit?

Which of the following statements about the use of control charts is/are FALSE?

In an electronics company that produces transistors,1000 transistors are inspected at regular intervals.The proportion of nonconforming transistors produced by the process,estimated from data collected in a 1-month period,is = 0.0026.What would be the value of the center line for a p chart of future samples of size 1000?

What is an R chart used for?

A control chart on a process characteristic has been shown to be in control.It has been determined that the process characteristic is approximately Normally distributed with an estimated mean = 36.5 and standard deviation = 1.25.The customer has indicated that the output from the process is acceptable if the measured characteristic is between a lower specification limit of 30 and an upper specification limit of 40.What are the estimated values of and ,respectively,for this process output?

Piston rings for an automotive engine are produced by a forging process.We wish to monitor the inside diameter of the rings manufactured by this process using an and an s control chart.Samples of size 4 are to be taken at regular intervals,and the sample means and standard deviations are computed and plotted on the charts in time order.The target values for the inside diameter are a mean of  = 75 millimeters and a standard deviation of  = 0.02 millimeters.The control chart constants are (partially)reproduced below. What is the center line for the Chart?

At the start of the semester,a professor wants to monitor students who miss class.The professor implements a new attendance policy geared toward encouraging students to attend class every day.There are currently 150 registered students in the class,and each day the class takes a quiz that is just used to measure attendance.The number of quizzes that are turned in will serve as the measure of attendance.The quizzes are given at every class period and the class meets four times per week over a 15-week semester.Suppose there were a total of 510 absences throughout this process.What is the average daily proportion absent?

Which of the following would produce an out-of-control signal in a control chart?

Which of the following is true about processes that are in control?

Piston rings for an automotive engine are produced by a forging process.We monitor the inside diameter of the rings manufactured by this process using an and an s control chart.Samples of size 4 are taken at regular intervals,and the sample means and standard deviations are computed and plotted on the charts in time order.The overall mean of the sample means is 73.812 millimeters,and the mean of the sample standard deviations is 0.022 millimeters.The control chart constants are (partially)reproduced below. What is the value of the center line of the s chart?

A bank is interested in improving the time it takes to complete transactions at teller windows.The goal is to have no transaction take more than 5 minutes.What name do we give the quantity "5 minutes"?