Question

An engineer has designed a valve that will regulate water pressure on an automobile engine. The valve was tested on 210 engines and the mean pressure was 5.0 pounds/square inch (psi). Assume the population standard deviation is 0.9. If the valve was designed to produce a mean pressure of 4.9 psi, is there sufficient evidence at the 0.02 level that the valve does not perform to the specifications?

Answer 1

H0: = 4.9

Ha: 4.9

Test statistics

z = ( - ) / ( / sqrt(n) )

= ( 5 - 4.9) / (0.9 / sqrt(210) )

= 1.61

Critical values at 0.02 level = 2.326

Since test statistics falls in non-rejection region, Do not reject H0.

We conclude at 0.02 level that we do not have sufficient evidence to support the claim that

the valve does not perform to the specifications.