What was Jochebed's reason for putting Baby Moses in a basket and placing him in the Nile? It would seem that by doing so she was sentencing the baby to certain death?
Was her intention for someone to find the basket and take care of Moses?
As the verse doesn't state what Jochebed's intentions were, the matter is open to speculation. The explanation you suggest is certainly a possibility. Doing nothing would have condemned Moses to death at the hands of the Egyptian death squads. Perhaps Jochebed was hoping that Moses would be found by a merciful Egyptian, and thus spared from death. Stationing Miriam close by would then allow her to see where Moses would end up, and hopefully allow her to initiate contact with her son at some later time.
The Biblical commentator Ibn Ezra suggests two reasons for placing Moses in the Nile: 1) If her son was meant to die, at the very least she wouldn't have to witness the unbearably painful scene of his execution (for a similar occurrence, see Genesis 21:15-16: "And [Hagar] cast the child under one of the bushes, and she went and sat down from afar, at about the distance of two bowshots, for she said, 'Let me not see the child's death.'") 2) Perhaps, Ibn Ezra postulates, Miriam prophetically informed her mother that this was the correct course of action for the moment.
The Talmud explains that Pharaoh originally decreed that the Jewish boys be cast into the river because his astrologers had predicted that water would be the catalyst for the "downfall" of the savior of the Jews. Based on this, the Midrash explains that Moses' mother -- who was aware of her son's special destiny -- hoped that as soon as Moses would be placed in the water, the astrologers would see that the savior of the Jews had already been "cast" into the water and the decree against the Jewish boys would be annulled, and she would be free to bring her son back home. This indeed is what happened but at that point it was too late; Pharaoh's daughter had already found Moses.
I hope that I've been helpful today.
Rabbi Menachem Posner