An engineer has designed a valve that will regulate water pressure on an automobile engine. The valve was tested on 160 engines and the mean pressure was 7.7 pounds/square inch (psi). Assume the population variance is 0.36. If the valve was designed to produce a mean pressure of 7.8 psi, is there sufficient evidence at the 0.01 level that the valve performs below the specifications?   Step 3 of 3: Make the decision to reject or fail to reject the null hypothesis.

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Q: A physical therapist wanted to know whether the mean step pulse of men was less than the mean step…

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