For df = 25, determine the value of A that corresponds to each of the following probabilites:
a. P(t >- A)= 0.025
b. P(t <- A)= 0.10
c. P(-A <- t <- A)=0.99
df = degrees of freedom
Look at the appropriate table (such as a t-table) to find the values you seek using df = 25 and the probabilities for a, b, and c.
I hope this will help get you started.