Jim Outfitters makes custom fancy shirts for cowboys. The shirts could be flawed in various ways, including flaws in the weave or color of the fabric, loose buttons or decorations, wrong dimensions, and uneven stitches. Jim randomly examined 10 shirts, with the following results:
The standard deviation of the number of defects is 3.559, and the mean is 6. So, lets look at how many shirts fall within 1, 2, and 3 standard deviations of the mean.
One standard deviation; 6 ± 3.559 = (2.441, 9.559): 6 shirts
Two standard deviations; 6 ± 7.118 = (-1.118, 13.118): 6 + 4 = 10 shirts
Three ...
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
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:
Upper Control Limit (UCL x-bar
I. (S6.10) A process that is considered to be in control measures an ingreidnet in ounces. Below are the last 10 samples (each of size n =5) taken.
(Sample numbers in the columns and individual observation results below)
1 2 3 4 5 6 7 8 9 10
10 9 13 10 12 10 10 13 8 10
9 9 9 10 10 10 11 10 8 12
10 11 10 11 9 8 10 8 12 9
9
This is for Quality Control
Consider the xbar chart for the piston-ring example as follows, let ring diameter be normally distributed, and the sample size is n = 5.
a) Find the two-sigma controllimits for this chart.
b) Suppose it was suggested that the two-sigma limits be used instead of the typical three-sigma limits.
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 upper and lower controllimits.
10. A travel agency is concerned with the accuracy and appearance of itineraries prepared for its clients. Defects can include errors in times, airlines, flight numbers, prices, car rental information, lodging, charge card numbers and reservation numbers, as well as typographical errors. As the possible number of errors is nearl
A critical dimension of the service quality of a call center is the wait time of a caller to get to a sales representative. Periodically, random samples of 6 (n = 6) customer calls are measured for time. Results from the last eight samples are shown in the following table.
Observation (seconds)
S 1 2 3 4 5 6
1 425 4
Which of the following patterns on an averages chart that displayed 25 sample averages would reveal an out of control process?
a - sample averages scattered in a seemingly random pattern within the 3-sigmacontrollimits
b - half the sample average above the center line and the other half below the center line
c - the first t
