Answer:
The decision rule is
Reject the null hypothesis
Step-by-step explanation:
From the question we are told that
The population mean is [tex]\mu = 5.6 \ pounds/inch^2[/tex]
The sample size is n = 160
The sample mean is [tex]\= x = 5.7 \ pounds/ inch^2[/tex]
The variance is [tex]\sigma ^2 = 0.25[/tex]
The level of significance is [tex]\alpha = 0.01[/tex]
The null hypothesis is [tex]H_o : \mu = 5.6[/tex]
The alternative hypothesis is [tex]H_a : \mu > 5.6[/tex]
Generally the standard deviation is mathematically represented as
[tex]\sigma = \sqrt{\sigma ^2 }[/tex]
=> [tex]\sigma = \sqrt{0.25 }[/tex]
=> [tex]\sigma = 0.5[/tex]
Generally the test statistics is mathematically represented as
[tex]z = \frac{\= x - \mu }{ \frac{\sigma}{\sqrt{n} } }[/tex]
=> [tex]z = \frac{5.7 - 5.6 }{ \frac{0.5 }{\sqrt{ 160 } } }[/tex]
=> [tex]z = 2.53[/tex]
From the z table the area under the normal curve to the left corresponding to 2.53 is
[tex]p-value = P(Z > 2.53 ) =0.0057[/tex]
From the value obtained we see that the [tex]p-value < \alpha[/tex] 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
