i have been reading dan harrington's book on tournament games. I came across this problem.

say we start the hand with 10 A..and someone else have 77..flop completety miss both of us..so i have 6 out for the turn and river combine to beat his 77..6 outs is about 24% to win..say 25% to make things more simple..so i have to get 1:4 odds to call if he raises me..but in dan harrington's book it says that we only need 1:3 odds to call if we have two over card to his pair..am i missing something?