Determine the t critical value for a two-sided confidence interval in each of the following situations. (Round your answers to three decimal places.) (a) Confidence level = 95%, df = 10 (b) Confidence level = 95%, df = 20 (c) Confidence level = 99%, df = 20 (d) Confidence level = 99%, n = 20 (e) Confidence level = 98%, df = 23 (f) Confidence level = 99%, n = 36