Question: 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 mean pressure of 7.3 lbs/square inch. The valve was tested on 210 engines and the mean pressure was 7.4 lbs/square inch. Assume the standard deviation is known to be 0.5 lbs/square inch. Is there evidence at the 0.05 level that the valve does not perform to the specifications?