Question

an engineer has designed a valve that will regulate water pressure on an automobile engine. The valve was tested on 290 engines and the mean pressure 4.1 pounds/square inch (psi). Assume the population standard deviation is 0.6. If the valve was designed to produce a mean pressure of 4.2 psi, is there sufficient evidence at the 0.02 level that the valve does not perform to the specifications?

FIND THE VALUE OF THE TEST STATISTIC AND IS THIS TWO TAILED OR ONE TAILED??!!!!!!

Answer 1

Solution - Given that, X = 4.1 6=0.6 na 290 di = 4.2 The null and alternative hypothesis Ho: M=4.2 Ha:ch 26.2 This is two-tailed test Test statistic, 2 = T-M z = 4.1-4.2 0.6/290 z = -2.838 The test statistic value = [-2.838]