an engineer has designed a valve that will regulate water pressure on an automobile engine. the valve was tested on 180 engines and the mean pressure was 6.2 lbs/square inch. assume the standard deviation is known to be 0.8. if the valve was designed to produce a mean pressure of 6.3 lbs/square inch, is there sufficient evidence at the 0.01 level that the valve does not perform to the specifications? state the null and alternative hypotheses for the above scenario.
