State the total degrees of freedom for the followingt-tests. (If you need to use, enter INFINITY.)

(a)n=12

for a one-independent samplet-test

(b)df₁=13,n₂=18

for a two-independent samplet-test

(c) critical value = 1.645 for a one-tailed test,= 0.05

(d) critical value = 63.657 for a two-tailed test,= 0.01