More STATS Vileness?

Question

For what value of ''c'' will the probability of : ( I(Xbar-mu)/S I <= c) =0.95 ?? n=21, mean = mu

Note that what may appear as an capital i or 1 denotes absolute value signs. I know that I have to use a t-statistic. and t_0.025, 20 = 2.086...Beyond here I'm stuck.

Answer 1

From "Z-tables":
c = 1.9600