Answer:
The decision rule is
Reject the null hypothesis
Step-by-step explanation:
From the question we are told that
The population mean is
The sample size is n = 160
The sample mean is
The variance is
The level of significance is
The null hypothesis is
The alternative hypothesis is
Generally the standard deviation is mathematically represented as
=>
=>
Generally the test statistics is mathematically represented as
=>
=>
From the z table the area under the normal curve to the left corresponding to 2.53 is
From the value obtained we see that the hence
The decision rule is
Reject the null hypothesis
The conclusion is
There is sufficient evidence to conclude that the believe that the valve performs above the specifications is true