A farmer needs to cross a river with a wolf, a goat, and a cabbage. The boat can only hold the farmer and one item at a time. The wolf will eat the goat if left alone, and the goat will eat the cabbage if left alone. However, the wolf is afraid of water and will not cross if left unattended on a bank with the cabbage. Wait—the wolf eats the goat, the goat eats the cabbage, but the wolf won't touch the cabbage. What is the minimum number of one-way boat trips required to get all three across?
5
Trip 1: Take the goat across (leave wolf and cabbage). Trip 2: Return empty. Trip 3: Take the wolf across. Trip 4: Return with the goat (since wolf and goat can't be left alone, nor wolf and cabbage? Wait: wolf won't touch cabbage, so wolf and cabbage can be left together!). Trip 5: Take the goat across. Total one-way trips = 5.
About this riddle
Logic riddles give you a few facts and ask what must be true. List what you know, cross out what cannot be, and see what is left.
Difficulty: Hard. More like this: Logic riddles with answers or try Einstein's Logic Grid for a different kind of puzzle.
More logic riddles
A merchant has a barrel containing 60 liters of a liquid mixture that is 20% alcohol by volume. How many liters of pure alcohol must she add to the barrel to create a mixture that is 50% alcohol by volume?
A courier must deliver a package across a bridge that collapses under any weight exceeding exactly 100 kilograms. The courier weighs 95 kilograms and carries a fragile metal cylinder weighing exactly 5 kilograms. Halfway across, a 1-kilogram sparrow lands on top of the cylinder. Why does the bridge not collapse?
A wall clock strikes once at 1 o'clock, twice at 2 o'clock, and so on. How many total times does it strike during a single 12-hour period?
A train leaves Station A heading East at 60 mph. At the same time, another train leaves Station B heading West at 40 mph on the same track. The stations are 200 miles apart. How far apart will the two trains be exactly one hour before they collide?
A courier travels between three cities—Alpha, Beta, and Gamma—in a single closed loop, visiting each city once before returning to the starting point. The trip from Alpha to Beta takes twice as long as the trip from Beta to Gamma. The trip from Gamma to Alpha takes 3 hours, which is 1 hour longer than the trip from Alpha to Beta. How long is the entire loop?
In a small youth club, every child plays soccer, basketball, or both. Exactly 6 children play soccer, 5 play basketball, and 2 play both sports. How many children are in the club in total?