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 7.4 pounds/square inch. It is believed that the valve performs above the specifications. The valve was tested on 190 engines and the mean pressure was 7.5 pounds/square inch. Assume the standard deviation is known to be 0.9. A level of significance of 0.1 will be used. Determine the decision rule.

Enter the decision rule.

Reject H0 if Z >

Answer 1

We have here,

Right tailed alternative hypothesis.

Z critical value =1.28..................by using Z table or Excel =NORMSINV(1-0.1)

Reject H0 if Z > 1.28