You are conducting a 1-way ANOVA with 5 groups with $\displaystyle \alpha={0.05}$.  A significant omnibus test indicates that at least one of the contrasts will be significant using the Scheffé test.  If the design was balanced with 27 subjects in each group, what is the critical value for the post hoc t-tests?
critical value =
      (report answer accurate to 3 decimal places)

Hint #1:  Find the degrees of freedom for the error (within) term.

Hint #2:  Find the F-ratio associated with the appropriate degrees of freedom for the significance level.