Topic 5 Quiz

The number of defects after a hotel room cleaning​ (sheets not​ straight, smears on​ mirror, missed debris on​ carpet, etc) should be measured using what type of control​ chart?

c-chart

The results of inspection of DNA samples taken over the past 10 days are given below. Sample size is 100. Day: 1 2 3 4 5 6 7 8 9 10 Defectives: 7 9 9 11 7 8 0 11 13 2 Give the upper and lower 3-sigma control chart limits. Given the limits, is the process in control for the following days? Day: 11 12 13 # of Defects: 8 11 13

UCLp = 0.157 LCLp = 0 Day: 11 - yes 12 - yes 13 - yes

The purpose of an ​x-bar chart is to determine whether there has been​ a:

change in the central tendency of the process output.

The ​c-chart signals whether there has been​ a:

change in the number of defects per unit.

Statistical process control​ charts:

display upper and lower limits for process variables or attributes and signal when a process is no longer in control.

Ten samples of a process measuring the number of returns per 100 receipts were taken for a local retail store. The number of returns were​ 10, 9,​ 11, 7,​ 3, 12,​ 8, 4,​ 6, and 11. Find the standard deviation of the sampling distribution for the ​p-bar chart.

.0273

A manager wishes to build a​ 3-sigma range chart for a process. The sample size is​ five, the mean of sample means is​ 16.01, and the average range is 5.3. From Table​ S6.1, the appropriate value of D3 is​ 0, and D4 is 2.115. What are the UCL and​ LCL, respectively, for this range​ chart?

11.2 and 0

Red Top Cab Company receives multiple complaints per day about driver behavior. Over 9 days the owner recorded the number of calls to be​ 3, 0,​ 8, 9,​ 6, 7,​ 4, 9, and 8. What is the upper control limit for the​ 3-sigma ​c-​chart?

13.35

Which of the following is true of a ​p-​chart?

The lower control limit may be at zero

Assignable​ causes:

are causes of variation that can be identified and investigated.

Natural​ variations:

are the many sources of variation that occur when a process is under control. when​ grouped, form a​ pattern, or distribution. affect almost every production process. are​ tolerated, within​ limits, when a process is under control. **All of the above are true.

To set ​x-bar chart upper and lower control​ limits, one must know the process central​ line, which is​ the:

average of the sample means

Control charts for variables are based on data that come​ from:

averages of small samples.

The number of late insurance claim payouts per 100 should be measured with what type of control​ chart?

p-chart

Auto pistons at Wemming​ Chung's plant in Shanghai are produced in a forging​ process, and the diameter is a critical factor that must be controlled. From sample sizes of 10 pistons produced each​ day, the mean and the range of this diameter have been as​ follows: Day: 1 2 3 4 5 Mean x-bar (mm): 154.9 153.2 155.6 157.5 156.6 Range R (mm): 4.0 4.6 4.1 5.0 4.7 What is the value of x-bar-bar? What is the value of R-bar? What are the UCLx and LCLx using 3-sigma? What are the UCLR and LCLR using 3-sigma?

x-bar-bar = 155.96mm R-bar = 4.52mm UCLx-bar = 157.35mm LCLx-bar = 154.57mm UCLR = 8.03mm LCLR = 1mm