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6166 UNIT 2 Section 3 Exercises

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You can choose to work some or all of the problems listed below. We recommend that you at least work the problems listed in your major area of interest. Answers to these questions are posted here (ANSWERS).
General Questions. 

For students in agriculture and environmental fields. 
Do problem 7.41, page 377. Concentrate on doing the Ftest for the difference in population variances. Given the results of this test, perform the associated two independent sample ttest for means? What do you conclude about the distributions of the two groups from these two tests? Think of a situation in your studies or research where testing the equality of variances would provide useful information? 
For students in engineering fields. 
Do problem 7.30, page 375. Concentrate on doing the Ftest for the difference in population variances. Given the results of this test, perform the associated two independent sample ttest for means? What do you conclude about the distributions of the two groups from these two tests? Think of a situation in your studies or research where testing the equality of variances would provide useful information? 
For students in toxicology and health science fields. 
Carbon monoxide (CO) concentrations (in ppm) were measured at two locations in San Jose, CA over a twomonth period. Summary data are presented below. Perform an Ftest for the difference in population variances. Given the results of this test, perform the associated two independent sample ttest for means? What do you conclude about the distributions of the two groups from these two tests? Class n Sample_Mean Sample_Std_Dev I 24 19.6 8.1 II 18 29.8 6.6 Think of a situation in your studies or research where testing the equality of variances would provide useful information? 
For students in community development, education and social services fields. 
A study was designed to evaluate whether socioeconomic factors have an effect on verbalization skills of young children. Assume two socioeconomic classes have been defined and random samples of similaraged children from each class have been tested. Summary statistics for a verbal skills test are presented below. Perform an Ftest for the difference in population variances. Given the results of this test, perform the associated two independent sample ttest for means? What do you conclude about the distributions of the two groups from these two tests? Site n Sample_Mean Sample_Std_Dev R1 54 3.4 3.8 R6 48 2.1 2.1 Think of a situation in your studies or research where testing the equality of variances would provide useful information? 