Problem 1.
L.L.Bean is an American, privately held retail company founded in 1912 by Leon
Leonwood Bean. The company is headquartered where it was founded, in Freeport,
Maine. It specializes in clothing and outdoor recreation equipment. A quality problem
that generates customer complaints occurs when a warehouse employee fills an order
with the wrong items. The company has decided to implement a process control plan by
inspecting the ordered items after they have been obtained from the warehouse and
before they have been packaged. The company has taken 30 samples (during a 30-day
period), each for 200 orders, and recorded the number of defective orders in each
sample. The sample can be found in the Excel file under the L.L.Bean tab.
Please, construct a P-chart for the company that describes 99.74% of the random
variation in the process and indicate if the process seems to be out of control at any
time. Explain your results.
Note: The total number of samples (30) is used to find the proportion average only.
The sample size (200) is used to find the proportion of each sample and the standard
deviation of the experiment.
Problem 2.
Telecom manufactures electronic components for computers. One measure it uses to
monitor the quality of its distribution process is the number of customer invoice errors.
The distribution center manager monitored the company’s order processing and
distribution by recording the number of invoice errors for 30 days. The sample results
can be found in the excel file under the tab “Telecom”.
Construct a c-chart with 3s limits for invoice errors and indicate if the process was out of
control at any time. Explain your results.
Problem 3.
The Elon Company manufactures parts for an aircraft company using three
computerized numerical controlled (CNC) turning centers. The company wants to
decide which machines can produce a specific part with design specifications of 0.097
inch +-0.015 inch.
The machines have the following process parameters
Machine 1: process mean=0.095, sigma=0.004
Machine 2: process mean=0.096, sigma=0.009
Machine 3: process range=0.093, sigma=0.002
Please, determine which machine (if any) can produce the products within design
specifications.
Sample Solution
