9.12 (other Levine text): Random samples of 60 listings in Farmingdale and 99 listings in Levittown yields the following mean and standard deviations (in thousands): Farmingdale:  sample mean = 191.33  std.dev.= 32.6 Levittown:     sample mean = 172.34  std.dev.= 16.92         (a)  At the 5% significance level, is there sufficient evidence of a difference in the average appraised values for homes?         (b)  Show the hypotheses, sample statistic, critical statistic and decision process in conducting the test.   Also, what does the p value of the test show?         (c)  Are the data likely to be sufficient for conducting this test?         (d)  Is this a one-tailed or two-tailed test?  What's the difference?  [Excel Note: you can download an Excel worksheet that conducts the separate variance t test for 2 means when the sample statistics are known by clicking here. Do not use PHStat's t test for two sample means because it assumes that the variances in the two groups are the same].  10.16 (c & b only)  Click here for the training.xls data file.  Also answer:           (f)  Show the hypotheses, sample statistic, critical statistic and decision process in conducting the test.   Also, what does the p value of the test show?          (g)  Create a side by side box plot of the two groups' assembly times.  What does it show? [Excel/Phstat Note:  In order to facilitate the generation of this test using Excel, first "unstack" the data using PHStat (click on <Phstat><DataPreparation><UnstackData>. You can then generate the t test using the raw data in the unstacked worksheet by clicking on  <Data><Data Analysis><t test: 2 sample assuming unequal variances>.   The side by side boxplot can be created by clicking on <PHStat><DescriptiveStats><Box&WhiskerPlot><MultipleGroups>.  10.29   Click here for the perform.xls data file and do the following:              (a)  Calculate the difference in performance ratings for each employee.              (b)  Using the calculated ratings difference, conduct a one sample t test (at the 5% level) on the mean difference (sigma unknown) to assess whether the seminars generated a significant increase in employee ratings.  Show the hypotheses, sample statistic, critical statistic and decision process in conducting the test.  PHSTAT Note:  Click on <PHStat><OneSampleTests><t test for the mean (sigma unknown)> and then highlight the difference in ratings column.              (c)  Using the preseminar and postseminar ratings for each employee, use EXCEL to conduct a t test for the mean difference in two related samples to assess whether the seminars generated a significant increase in employee ratings (click on <Data><Data Analysis><t test: paired two sample for means> and then highlight the two columns of ratings).  Compare these findings w/ those of the one sample test.  What hypotheses does the t test for the mean difference in two related samples really test?