An engineer designed a valve that will regulate water pressure on an automobile engine. The engineer designed the valve such that it would produce a

find the hypothesis, the  test statistic,

An engineer designed a valve that will regulate water pressure on an automobile engine. The engineer designed the valve such that it wouldproduce a mean pressure of 7.2 lbs/square inch. The valve was tested on 250 engines and the mean pressure was 7.3 lbs/square inch. Assume thevariance is known to be 0.49. Is there evidence at the 0.05 level that the valve performs above the specifications?