1. Which of the following situations suggest a process that appears to be operating in a state of statistical control?

a. A control chart with a series of consecutive points that are above the center line and a series of consecutive points that are below the center line.

b. A control chart in which no points fall outside either the upper control limit or the lower control limit and no patterns are present.

c. A control chart in which several points fall outside the upper control limit.

d. All of the above.

2. A quality control analyst for a light bulb manufacturer is concerned that the time it takes to produce a batch of light bulbs is too erratic. Accordingly, the analyst randomly surveys 10 production periods each day for 14 days and records the sample mean and range for each day.

Referring to the table, suppose the analyst constructs an R chart to see if the variability in production times is a control. What is the lower control limit for this R chart?

a. 4.84
b. 3.37
c. 2.98
d. 1.34

3. A political pollster randomly selects a sample of 100 voters each day for 8 successive days and asks how many will vote for the incumbent. The pollster wishes to construct a p chart to see if the percentage favoring the incumbent candidate is too erratic.

(Problem attached in excel file)
Sampling four pieces of precision-cut wire (to be used in computer assembly) every hour for the past 24 hours has produced the following results:
Hour X in " R in "
1 3.25 0.71
2 3.1 1.18
3 3.22 1.43
4 3.39 1.26
5 3.07 1.17
6 2.86 0.32
7 3.05 0.53
8 2.65 1.13
9 3.02 0.71
10 2.85

We have taken 12 samples of 400 letters each from a typing pool and found the following proportions of defective letters: 01, .02, .02, .00, .01, .03, .02, .01, .00, .04, .03 and .02. A letter is considered defective when one or more errors are detected.
Questions:
1. Calculate the center line, upperandlowercontrol limi

Find the upperandlowercontrollimits for /x- and R-charts for the width of a chair seat when the sample grand mean (based on 30 samples of 6 observations each) is 27.0 inches, and the average range is 0.35 inches.

See attached file.
Factors for computing control chart limits (3 sigma) for this problem
Cordelia Barrera is attempting to monitor a filling process that has an overall average of 715 cm3
The average range R is 6 cm3
For a sample size of 10 the controllimits for 3-sigma x-bar chart are:
UpperControl Limit (UCL x-bar

As the production manager for an electronic circuit company you have encountered the following situation.
Part 1
A process for producing electronic circuits has achieved very high yield levels. An average of only 10 defective parts per million is currently produced.
What are the upperandlowercontrollimits for a samp

Control charts are graphs that show upperandlowerlimits for a process an organization wants to control, depicting a graphic presentation of data over time. A control chart can indicate a process is out of control by showing the target line, and plotting actual performance against the line (Render, Stair & Hanna, 2011). When t

The smallest defect in a computer chip will render the entire chip worthless. Therefore, tight quality control measures must be established to monitor the chips. In the past, the percentage defective for these chips has been 1.1%. The sample size is 1,000. Determine the upperandlowercontrol chart limits for these computer

For the following data use the weighting constant x = 0.5 and exponential smoothing to determine the forecast for 2005.
Subscribers Subscribers
Year (millions) Year (Millions)
1993 16.0 1999 86.0
1994 24.1 2000

What might cause a process to be out of control?
Explain why a process can be out of control even though all samples fall within the upperandlowercontrollimits.

1. The overall average on a process you are attempting to monitor is 49 units. The process standard deviation is 1.52. Determine the upperandlowercontrollimits for a mean chart, if you choose to use a sample size of 5. Set z=3.
UCLx = ____________
LCLx = ____________
Round your answers to 2 decimal places; for examp