Solutions…
11.45
Open the data set XR11-45
Parametric tests
One-sample t-test and z-test
Follow the steps on page 345 – with Significance level (%) = 5 and Variance =
2500
Excel output:
Interpretation
H0 : μ = 560
H1: μ > 560
Will accept H0 if z Stat < 1.6449
Will reject H0 if z Stat > 1.6449
z Stat = 0.895 < 1.6445 → Accept H0
or
Will accept H1 if the p-value is small
P-value = 0.21 → overwhelming evidence to reject H1
Conclusion
The dean's claim is not true on a 5% level of significance - GMAT
score did not increase during the past 5 years
11.46
Open the data set XR11-46
Parametric tests
One-sample t-test and z-test
Follow the steps on page 345 – with Significance level (%) = 10 and Variance
= 14.9769
Excel output:
Interpretation
H0 : μ = 17.85
H1: μ >17.85
Will accept H0 if z Stat < 1.282
Will reject H0 if z Stat > 1.282
z Observed = 1.656 > 1.282 → Accept H1
or
Will accept H1 if the P-valuel is small
P-value = 0.0489 → overwhelming evidence to accept H1
Conclusion
The campaign was successful on a 10% level of significance - the
average amount spend on long distance telephone accounts
did increase
We must assume that the population standard deviation is still 3.87 and
that the data is normally distributed