"If he is eating, he is probably hungry."
Translation:אם הוא אוכל, אז סביר להניח שהוא רעב.
No. It is in fact not entirely correct, formally. אז should only refer to time description. But in everyday conversation we use it a lot, incorrectly, as the "then" component in "if-then". You could quite correctly say אם הוא אוכל, סביר להניח שהוא רעב, it would also sound ok conversationally, not too formal.
The second clause of the Hebrew answer is something I would think to translate into English as "then it is probable that he is hungry." That feels different to my ear (as a native English speaker) from "he is probably hungry." Can you comment? (And I've read the earlier discussion about whether אז is needed, so no need to comment on that aspect.)