“~hazu” means “should / must / ought to”
Q: Kobayashi san ga mada kimasen.
Q: Kobayashi has not come yet.
A: Sō desu ka. Watashi yori saki ni, uchi o deta hazu desu ga.
A: Is it. He came out earlier than me, he should have gone out
Q: Ashita 8 jihan made ni kaisha e ikitai desu ga, nanji no densha ni nottara(noru) ii deshō ka?
Q: I would like to reach office at 8.30, what time of the train should I take?
A: 7 ji 45 fun no de maniau hazu desu.
A: You should be on time by taking the 7.45 train.
Q: Otōto-san wa, go ryōshin ga jiko ni atta koto o shitte iru deshō ka?
Q: Does your brother know that your parent had an accident.
A: Iie, otōto wa mada shiranai hazu desu
A: No, he should not know about it yet.