Question

Create appropriate control charts and interpret the results for the following problem.

Question: Before shipping lawn mowers to dealers, an employee starts each mower and records data for mowers that dont start on the first try. Out of 100 mowers, an average of four did not start.

Answer 1

When we deals with several samples, each with many observations and have fraction, proportion or percent defective, we use p-chart (for attribute data, i.e. data can be categorized in two states).

Now, the control limits for the p-Charts is obtained using the formula,

Where,

Now,

For three sigma standard deviation within mean fraction defective, the process will be in control if the mean fraction of defective are within range (0.00000, 0.098788)