A Car Mechanic Is Thinking of Guaranteeing Customers That an Oil

question 8

Essay

A car mechanic is thinking of guaranteeing customers that an oil change will take no more than 15 minutes with a 99.73% confidence level. He takes a few samples of size 5 and finds the process mean to be 13 minutes with a standard deviation of .2 minutes and average sample range of 1.2 minutes. Find the A₂, D₄, and D₃ values and use them to compute the upper and lower limits for an x-bar chart. Use the upper limit to determine if the mechanic can offer a 15 minute guarantee. Assume the mechanic plots the samples on the x-bar control chart and finds the process is in control, is there anything else the mechanic is missing to ensure the process is in control?

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Definitions:

Behaviourism

Behaviourism is a psychological approach that emphasizes the study of observable behaviors and their environmental determinants, ignoring internal mental states.

Overcompensation

A psychological term referring to the process of making up for perceived deficiencies and weaknesses by emphasizing strengths or developing new abilities.

Alfred Adler

An Austrian medical doctor and psychotherapist who founded the school of individual psychology, emphasizing the importance of feelings of inferiority and social interest.

Sports Car

A vehicle designed for high speed and performance, with great emphasis on handling, agility, and aesthetic appeal.