Use the d_logret_6stock dataset to answer the questions. (1) Perform a t-test for American Express with the null hypothesis that the mean of its return is zero. (2) Perform a Wilcoxon signed-rank test...

Use the d_logret_6stock dataset to answer the questions. (1) Perform a t-test for American Express with the null hypothesis that the mean of its return is zero. (2) Perform a Wilcoxon signed-rank test for American Express with the null hypothesis that the mean of its return is zero. (3) Perform a two-sample t-test to conclude if the mean returns of Pfizer and American Express are same or not. (4) Perform a two-sample Wilcoxon test to conclude if the mean returns