Determine the t-value in each of the cases. (a) Find the t-value such that the area in the right tail is 0.025 with 15 degrees of freedom. 2.131 (Round to three decimal places as needed.) (b) Find the t-value such that the area in the right tail is 0.25 with 20 degrees of freedom. 0.687 (Round to three decimal places as needed.) (0) Find the t-value such that the area left of the t-value is 0.05 with 17 degrees of freedom. [Hint: Use symmetry.] - 1.740 (Round to three decimal places as needed.) (d) Find the critical t-value that corresponds to 60% condence. Assume 15 degrees of freedom. lI (Round to three decimal places as needed.)