The average dividend yield of a random sample of 28 JSE-listed companies last year was found to be 12.5%, with a sample standard deviation of 3.4%. Assume that dividend yields are normally distributed.
(a) Calculate, with 90% confidence, the actual mean dividend yield of all JSE-listed companies last year. Interpret the finding.
(b) Compute the confidence interval in (a) using Excel's TINV formula.