21stcenturycyber
21stcenturycyber
04.05.2021 • 
Mathematics

The piston diameter of a certain hand pump is 0.7 inch. The manager determines that the diameters are normally​ distributed, with a mean of 0.7 inch and a standard deviation of 0.003 inch. After recalibrating the production​ machine, the manager randomly selects 25 pistons and determines that the standard deviation is 0.0022 inch. Is there significant evidence for the manager to conclude that the standard deviation has decreased at the α=0.05 level of​ significance?

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