Question

An engineer has designed a value that will regulate water pressure on an automobile engine. The valve was tested on 120 engines and the mean pressure was 4.6 pounds/square inch. Assume the variance is known to be 0.64. If The valve was designed to produce a mean pressure of 4.4 pounds/square inch, is there sufficient evidence at the 0.1 level that the Valve performs above the specifications? State the null and alternative hypothesis for the above scenario

Answer 1

The valve was designed to produce a mean pressure of 4.4, this means that our null hypothesis has to be:

$H_0:\mu=4.4$

Since we want to determine if there is sufficient evidence that the valve is aboce the specifications, this means that we want to determine if the mean is greater than 4.4, that is, the alternartive hypothesis is:

$H_a:\mu>4.4$