Answer:
Step-by-step explanation:
Here are the missing values;
Mean μ = 15.5 minutes
Standard deviation = 1.7 minutes
A Random sample of 90 completion
The sample mean = 15.4 minutes
Level of significance = 0.1
Then the following analysis can be made on the above study.
Firstly, the null hypothesis is [tex]\mathbf{H_o : \mu = 15.5}[/tex]
the alternative hypothesis is [tex]\mathbf{H_a: \mu < 15.5}[/tex]
Since, the value is less than, then this is a one-tailed test.
The Z test statistics can be computed as:
[tex]Z = \dfrac{ \overline x - \mu }{\dfrac{\sigma}{\sqrt{n}} } \ \ \sim \ \ N(0.1)[/tex]
[tex]Z = \dfrac{ 15.4-15.5 }{\dfrac{1.7}{\sqrt{90}} }[/tex]
[tex]Z = \dfrac{ -0.1 }{\dfrac{1.7}{ 9.4868} }[/tex]
Z = −0.560
The critical value of Z at 0.1 level of significance is:
[tex]Z_{0.1} = -1.28[/tex]
Decision Rule: We fail to reject the null hypothesis sInce -0.560 > -1.28
Conclusion: NO, there is no evidence to support the claim that the mean completion time has decreased. We conclude that the mean completion time remains at 15.5 minutes.
