QUESTION 4 The depression scores (the higher the score, the more stressed are the patients) of 25 patients were recorded before and after they had undergone a therapy. The scores were analyzed to see the effectiveness of the therapy. The outputs are indicated below. Paired Samples Statistics Mean N Std. Deviation Std. Error Mean Pair 1 depress1 42.56 25 4.331 866 depress2 41.36 25 4.957 991 Paired Samples Test Paired Differences df Sig. Mean Std. Std. Error 95% Confidence (2-tailed) Deviation Mean Interval of the Difference Lower Upper Pair 1 depress1 - depress2 2.121 324 2.076 2.828 24 009 Note: depress1 is representing the depression scores before the patient undergo a therapy Assuming the score of depression is normally distributed. a) Find the values of X and Y. (3 marks) b) State the 95% confidence interval for the mean depression scores. (1 mark) c) Based on the confidence interval in b), can it be concluded that the therapy is effective? (2 marks)