Finding Lower Critical F Values In this section, for hypothesis tests that were two- tailed, we found only the upper critical value. Let's denote that value by FR, where the subscript indicates the critical value for the right tail. The lower critical value FL (for the left tail) can be found as follows: First interchange the degrees of freedom, and then take the reciprocal of the resulting F value found in Table A-5. (FR is sometimes denoted by Fa>2 and FL is sometimes denoted by F12a>2.) Find the critical values FL and FR for two-tailed hypothesis tests based on the following values.

a. n1 5 10, n2 5 10, a 5 0.05

b. n1 5 10, n2 5 7, a 5 0.05

c. n1 5 7, n2 5 10, a 5 0.05.