Determine the upper-tail critical value t/2 in each of the following circumstances. a. 1-a= 0.99, n= 53 d. 1-a=0.99, n= 22 b. 1-a = 0.90, n = 53 e. 1-a = 0.95, n= 61 c. 1-a = 0.99, n 39 a. t= (Round to four decimal places as needed.) b. t= 1.674 (Round to four decimal places as needed.) c. t= (Round to four decimal places as needed.) d. t= (Round to four decimal places as needed.) e. t= (Round to four decimal places as needed.)