Question 10 (Quality Control): 15 points

In November 2002, John Wells, a customer service representative of Bayfield Mud Company, was summoned to the Houston Warehouse of Wet-Land Drilling, Inc. to inspect three boxcars of mud-treating agents that Bayfield had shipped to the Houston firm. Wet-Land has filed a complaint that the 50-pound bags of treating agents just received from Bayfield were short-weight by approximately 5%.

The short-weight bags were initially detected by one of Wet-Land’s receiving clerks, who noticed that the railroad scale tickets indicated that net weights were significantly less on all three boxcars than those of identical shipments received on October 25, 2002. Bayfield’s traffic department was called to determine if lighter weight pallets were used on the shipments. Bayfield indicated that no changes had been made in loading and palletizing procedures. Thus, Wet-Land engineers randomly checked 50 bags and discovered that the average net weight was 47.51 pounds. They noted from past shipments that the process yielded bag net weights averaging exactly 50.0 pounds with an acceptable standard deviation of 1.2 pounds. Consequently, they concluded that the sample indicated a significant short-weight. (You may wish to verify this conclusion) Bayfield was then contacted, and Wells was sent to investigate the complaint. Upon arrival, Wells verified the complaint and issued a 5% credit to Wetland.

Wet-Land management was not completely satisfied with the issuance of credit. The short-weight bags could cause severe economic consequences. Thus, Wet-Land informed Wells that they may seek a new supplier if the bags received in the future significantly deviated from 50 pounds.

The Quality Control department suspected that the lightweight bags may have resulted from "growing pains" at their plant. In the fall of 2002, Bayfield had to expand from a one-shift operation (6AM to 2PM) to a three-shift operation (24 hours/day) to cope up with increase in demand.

The additional night-shift bagging crew was staffed entirely by new employees. The most experienced foremen were temporarily assigned to supervise the night-shift employees. Most emphasis was placed on increasing the output of bags to meet the ever increasing demand. It was suspected that only occasional reminders were made to double check the weight feeder.

To verify this expectation, the QC department staff randomly sampled the bag output and the prepared the following data table. A sample of six bags was taken each hour.

Analyze the problem using all possible statistical quality control tools.

Prepare:

- a spreadsheet that shows all the computations you have made.

- a document that explains the process you have gone through (your additional assumptions etc.) and your results.

Price: $12.78

Solution: The downloadable solution consists of 7 pages, 578 words and 3 charts.
Deliverable: Word Document