Consider an Engine Parts Supplier,and Suppose the Supplier Has Determined

question 44

Essay

Consider an engine parts supplier,and suppose the supplier has determined that the mean and variance of the population of all cylindrical engine part outside diameters produced by the current machine are,respectively,2.5 inches and .00075.To reduce this variance,a new machine is designed.A random sample of 20 outside diameters produced by this new machine has a sample mean of 2.5 inches,a variance of s² = .0002 (normal distribution).In order for a cylindrical engine part to give an engine long life,the outside diameter must be between 2.43 and 2.57 inches.Find the 95 percent confidence intervals for σ² and σ for the new machine.

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Definitions:

Cohen's D

Cohen's d is a statistic used to quantify the difference between two means, measured in standard deviations.

Cohen's D

A measure of effect size indicating the standardized difference between two means.

Standard Deviation Units

Units measured in terms of the number of standard deviations away from the mean of the distribution.

Cohen's D

A measure of effect size indicating the standard deviation difference between two means.