The farmer has taken the goat across and come back, then taken the wolf across. What must he do before leaving the wolf?

Leave both and fetch the cabbage

In the fastest solution to the bridge and torch puzzle, which two people cross together in the middle trip?

The 5-minute and 10-minute people

The 1-minute and 10-minute people

The 2-minute and 5-minute people

Why does someone always have to walk back across the bridge?

To return the torch to those still waiting

To count the people who crossed

In the wolf, goat and cabbage puzzle, why is the goat the key to the solution?

It is the only one that clashes with both others

River Crossing Puzzles: Wolf, Goat, Cabbage and More

These river crossing puzzles test your planning skills with the classic farmer, wolf, goat and cabbage problem, the bridge and torch puzzle, missionaries and cannibals and a family on a small raft, plus the history of these puzzles, which go back to the scholar Alcuin of York at the court of Charlemagne more than 1,200 years ago. Ten questions.

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🎯 Daily Trivia Challenge • 🧠 10 Questions • ⏱️ 90 Seconds

Question 1 / 10 Time: 90s

Wolf, goat, cabbage
A farmer must take a wolf, a goat and a cabbage across a river in a boat that holds him and one more item. The wolf eats the goat and the goat eats the cabbage if left alone. What should he take first?
Wolf, goat, cabbage
The farmer has taken the goat across and come back, then taken the wolf across. What must he do before leaving the wolf?
Wolf, goat, cabbage
What is the smallest number of one-way boat trips needed to solve the wolf, goat and cabbage puzzle?
History
The oldest known river crossing puzzles appear in a collection linked to which medieval scholar?
Bridge and torch
Four people must cross a bridge at night with one torch. At most two cross at once, walking at the slower person's pace. They take 1, 2, 5 and 10 minutes. What is the shortest total time?
Bridge and torch
In the fastest solution to the bridge and torch puzzle, which two people cross together in the middle trip?
Bridge and torch
Why does someone always have to walk back across the bridge?
Missionaries
Three missionaries and three cannibals must cross a river in a boat for two. Cannibals may never outnumber missionaries on either bank. What is the fewest number of one-way crossings?
Raft
Two adults and two children must cross a river. Their raft carries one adult or up to two children. What is the first move?
Strategy
In the wolf, goat and cabbage puzzle, why is the goat the key to the solution?

Explanations: answer key for all 10 questions

Q1: A farmer must take a wolf, a goat and a cabbage across a river in a boat that holds him and one more item. The wolf eats the goat and the goat eats the cabbage if left alone. What should he take first?
Answer: The goat
Taking the goat first is the only safe move, because the wolf does not eat cabbage. Taking either of the others would leave the goat with something it eats or is eaten by.
Q2: The farmer has taken the goat across and come back, then taken the wolf across. What must he do before leaving the wolf?
Answer: Take the goat back with him
If he leaves the wolf with the goat, the goat is eaten. So he brings the goat back, takes the cabbage over, and finally returns for the goat.
Q3: What is the smallest number of one-way boat trips needed to solve the wolf, goat and cabbage puzzle?
Answer: 7
The trips are: goat over, back alone, wolf over, goat back, cabbage over, back alone and goat over. That makes 7 crossings.
Q4: The oldest known river crossing puzzles appear in a collection linked to which medieval scholar?
Answer: Alcuin of York
They appear in Propositiones ad Acuendos Juvenes, problems to sharpen the young, a Latin collection linked to Alcuin of York, a scholar at Charlemagne's court around 800.
Q5: Four people must cross a bridge at night with one torch. At most two cross at once, walking at the slower person's pace. They take 1, 2, 5 and 10 minutes. What is the shortest total time?
Answer: 17 minutes
The 1 and 2 cross (2), the 1 returns (1), the 5 and 10 cross (10), the 2 returns (2) and the 1 and 2 cross again (2). That totals 17 minutes.
Q6: In the fastest solution to the bridge and torch puzzle, which two people cross together in the middle trip?
Answer: The 5-minute and 10-minute people
Sending the two slowest people together means the 10-minute walk also covers the 5-minute person. Most first guesses send the fastest person with everyone, which takes 19 minutes.
Q7: Why does someone always have to walk back across the bridge?
Answer: To return the torch to those still waiting
Nobody can cross without the torch, and there is only one. So after each forward trip, someone must bring it back, and the trick is choosing who.
Q8: Three missionaries and three cannibals must cross a river in a boat for two. Cannibals may never outnumber missionaries on either bank. What is the fewest number of one-way crossings?
Answer: 11
The shortest known solution takes 11 crossings. This puzzle became a famous test problem in early artificial intelligence research.
Q9: Two adults and two children must cross a river. Their raft carries one adult or up to two children. What is the first move?
Answer: Both children cross together
Both children cross, and one brings the raft back. Then an adult crosses, and the other child brings the raft back. The pattern repeats for the second adult.
Q10: In the wolf, goat and cabbage puzzle, why is the goat the key to the solution?
Answer: It is the only one that clashes with both others
The goat is in danger from the wolf and is a danger to the cabbage. The wolf and the cabbage are safe together, so the goat must be moved most often.

River Crossing Puzzles – Planning Every Move

River crossing puzzles are some of the oldest logic puzzles in the world. A group of people, animals or objects must cross a river using a small boat, but there are rules: the boat holds only a few passengers, and certain pairs cannot be left alone together. The challenge is to find a series of trips that gets everyone across safely.

The best-known version is the wolf, goat and cabbage puzzle. It appears in a Latin collection called Propositiones ad Acuendos Juvenes, meaning problems to sharpen the young, which is linked to Alcuin of York. Alcuin was an English scholar who taught at the court of the emperor Charlemagne around the year 800. The same collection includes other crossing puzzles, such as jealous husbands.

Modern variations add new twists. In the bridge and torch puzzle, four people with different walking speeds must share a single torch at night. In missionaries and cannibals, one group must never be outnumbered on either bank. That puzzle became a famous test for early computer programs in artificial intelligence.

The key to solving them is often a counterintuitive move: bringing something back across the river. Many people resist going backward, but the solution to the wolf, goat and cabbage puzzle depends on returning the goat. In the bridge puzzle, the trick is to send the two slowest people together.

Solvers can draw both banks on paper and track every item after each trip. Computer scientists model the same puzzles as states and moves, searching for the shortest path from start to finish.

River crossing puzzles teach patience, planning ahead and checking every step, skills that help in projects, games and everyday problem solving.

What This Quiz Teaches

This quiz is perfect for puzzle lovers, families and future programmers.

How to solve the wolf, goat and cabbage puzzle
The bridge and torch puzzle
Missionaries and cannibals
Why moving backward can help
Tracking states and trips
Alcuin of York and Charlemagne

Quick Facts About River Crossing Puzzles

Alcuin's collection includes more than 50 math and logic problems.
Some versions use a fox, a goose and a bag of beans.
Versions of the wolf, goat and cabbage puzzle are told in folk tales in many countries.
The bridge and torch puzzle is popular in job interviews.
River crossing puzzles are used to teach search methods in computer science.
Many video games include river crossing challenges.