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The Japanese IQ Test

Supposedly this is given as a test in Japan. I have no idea if that’s accurate.

There are 8 people who have to cross the river on a raft.

1. Policeman
2. Thief
3. Father
4. Boy 1
5. Boy 2
6. Mother
7. Girl 1
8. Girl 2

The rules are:

Only two people can cross at a time.
Only the adults can operate the raft.
The father can’t be with the girls unless the mother is there.
The mother can’t be with the boys unless the father is there.
The thief can’t remain with anyone unless the policeman is present.

How do you get them all across?

Instead of working it out by hand, here’s a flash version.

Click on the circle to start. Click on a person to put them on the raft and click on the lever to make the raft cross.

Here’s how I did it in 17 steps. Can you do it faster? Let me know in the comments.

1. Policeman (P)
2. Thief (T)
3. Father (F)
4. Boy 1 (B1)
5. Boy 2 (B2)
6. Mother (M)
7. Girl 1 (G1)
8. Girl 2 (G2)

1. P, T →
2. ← P

3. P, B1 →
4. ← P T

5. F, B2 →
6. ← F

7. F, M →
8. ← M

9. P, T →
10. ← F

11. M, F →
12. ← M

13. M, G1 →
14. ← P T

15. P, G2 →
16. ← P

17. P, T →


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12 Comments on "The Japanese IQ Test"


Zee says
November 13, 2014 @ 16:09

You know why this is hard?

What kind of police officer would carry a thief across a river, then leave them there to row back? What’s to stop the thief from running away?

Using common sense, I just broke this riddle’s answer at step 2, and yet someone designed 17 steps.


Dan says
November 13, 2014 @ 16:11

The police officer could cuff the thief to a tree :)


Rei says
September 1, 2015 @ 20:23

1. Policeman (P)
2. Thief (T)
3. Father (F)
4. Boy 1 (B1)
5. Boy 2 (B2)
6. Mother (M)
7. Girl 1 (G1)
8. Girl 2 (G2)

1.M, G1 →
2. ← M

3. M, G2 →
4. ←M

5. F, B1→
6. ← F

7. F, B2 →
8. ← F

9. F, M→
10. ← F

11. P, T →
12. ← M

13. M,F →


John says
October 7, 2015 @ 16:22

Rei you are wrong. The mother can not be alone with the boys and neither can the father be alone with the girls.


Reflection says
December 4, 2015 @ 01:57

1. F, B1
2. F
3. F, B2
4. F
5. F, M
6. M
7. P, T
8. F
9. M, F
10. M
11. M, G1
12. M, F
13. M, G2
14. M
15. M, F


Kyung bulla says
January 20, 2016 @ 05:49

1. P,T>>
2. <>
4. <>
6. F,B1>>
7. P,B2>>
8. <>


Little Mrs. Spoiler says
March 4, 2016 @ 15:39

1. Policeman (P)
2. Thief (T)
3. Father (F)
4. Boy 1 (B1)
5. Boy 2 (B2)
6. Mother (M)
7. Girl 1 (G1)
8. Girl 2 (G2)

1. P, T →
2. ← P

3. P, B1 →
4. ← P T

5. F, B2 →
6. ← F

7. F, M →
8. ← M

9. P, T →
10. ← F

11. M, F →
12. ← M

13. M, G1 →
14. ← P T

15. P, G2 →
16. ← P

17. P, T →


Kuroka says
April 7, 2016 @ 17:03

I think 17 steps is the best, all the people who’ve said they’ve done less in the comments have left the mother / father alone with one of the children of the opposite gender


coldzaon says
August 9, 2016 @ 13:06

1.father with b1
2 father goes back
3father with b2
4 mother with g1
5 mother come back
6 mother with g2
7 police man with thief
Sorry if made a mistake or if I’m not supposed to do something in this


MelloJello says
November 20, 2016 @ 18:51

Couldn’t this be done like this? EH Just tryna help here

1. P/T
2. Push raft back w/stick
3. M/G1
4. M goes back
5. M/G2
6. Push raft back w/stick
7. F/B1
8. F goes back
9. F/B2


MelloJello says
November 20, 2016 @ 18:51

NEVERMIND I just realized mother would be with boy NVM


xxxCATxxx says
November 20, 2016 @ 19:00

I can solve it in 1 step: Everyone swims.


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