Topic: River crossing puzzle

Today we learned about river crossing puzzle. It is a fun problem that requires multi-step solution, logical reasoning, thinking one step ahead, and keeping track the movement of all parts (e.g. which person is on which side, and which side is the boat at, etc). Review the notes to see how we use a table of two rows to record steps of the crossing.

Homework

1. A man weighing 80 kg and his two children, each weighing 40 kg, want to cross a river. Each can row the boat they must use. The boat can carry only 80 kg. What is the least number of crossings that can be made to get from one side of the river to the other? (A crossing means going from one side of the river to the other side -- not a round trip)

A) 1       B) 3          C) 5          D) 7            E) 9

2. A man has to take a wolf, a goat, and some cabbage across the river. The rowboat has enough room for the man plus either the wolf or the goat or the cabbage. If he takes the cabbage with him, the wolf will eat the goat. If he takes the wolf, the goat will eat the Cabbage. Only when the man is present are the goat and cabbage safe. How can he get everything across the river?