Answer to #4. It takes 7 crossings. First he leaves the wolf and cabbage on the left bank and takes the goat to the other side. He returns with the boat empty. Then he takes the wolf across, leaving the cabbage behind. On the return trip he leaves the wolf on the right bank and brings the goat back (to keep it safe from the wolf). Next he takes the cabbage across, leaving the goat on the left bank. With the wolf and cabbage on the right bank, he returns to get the goat, taking it across on the final trip.