The average dividend yield of a random sample of 20 JSE-listed companies this year was found to be 14.5%, with a sample standard deviation of 3.4%. Assuming that dividend yields are normally distributed: a. calculate, with 90% confidence, the actual mean dividend yield of all JSE-listed companies this year. Interpret the findings. (8) b. calculate, with 98% confidence, the actual mean dividend yield of all JSE-listed companies this year. (8) c. compare and comment on the intervals calculated above. (4)