please help

(a) Find the t-value such that the area in the right tail is 0.005 with 17 degrees of freedom (Round to three decimal places as needed.) (b) Find the t-value such that the area in the right tail is 0.025 with 13 degrees of freedom. (Round to three decimal places as needed.) (c) Find the t-value such that the area left of the t-value is 0.05 with 30 degrees of freedom. (Hint: Use symmetry.] (Round to three decimal places as needed.) (d) Find the t-value that corresponds to building a 80% confidence interval. Assume 12 degrees of freedom. (Round to three decimal places as needed.)