Use the Traditional Method to Test the Given Hypothesis

question 9

Essay

Use the traditional method to test the given hypothesis. Assume that the population is normally distributed and that the sample has been randomly selected.
-When 12 bolts are tested for hardness, their indexes have a standard deviation of 41.7. Test the claim that the standard deviation of the hardness indexes for all such bolts is greater than 30.0. Use a 0.025 level of significance.

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Definitions:

Covariance

A measure of how much two random variables change together.

Standard Deviation

A measure of the amount of variation or dispersion of a set of values; quantifies how much the values of a dataset deviate from the mean.

Interquartile Range

A measure of statistical dispersion, which is the difference between the first and third quartiles in a dataset, showing the spread of the middle 50% of values.

Closing Stock Price

The last price at which a stock is traded on a particular trading day, representing the final market valuation of the stock for that day.