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QUESTION 4 A professor at a local university wish to determine whether there is a significant difference in the average of final examination marks between the students who took his STA404 course online and face-to-face. Fifteen students were randomly selected from each group and the final examination marks were recorded. Hence, he analysed the data using IBM SPSS and the results are as follows. Independent Samples Test Mark Equal variances Equal variances assumed not assumed Levene's Test for Equality of F 2.041 Variances Sig. 164 t-test for Equality of Means t -1.524 -1.524 df W 24.625 Sig. (2-tailed) 139 140 Mean Difference -6.42000 -6.42000 Std. Error Difference 4.21320 4.21320 95% Confidence Interval of Lower X -15. 10390 the Difference Upper Y 2.26390 a) Are the variances of the two populations equal? Use a=0.05. (3 marks) b) Find the value of W. (1 mark)c) Calculate the values of X and Y. (4 marks) d) Based on the confidence interval obtained in c), is there any evidence to support that the average of final examination marks for students who took online class is different from face-to-face class? Give a reason to support your answer. (2 marks)