#14 on page 405 for A.
I get that you’re supposed to use the F-Test. I get that when you go to the F-table, you have to use k and (n-(k+1)) to figure out a critical value. To me in this case you are using 3 for k, and 152 for n-(k-1). The answer agrees with me.
But they also state in the answer, "From the F-test table, the critical value for F(3,120) = 2.68. Why is this relevant? Where did they get the 120 from?