Japanese IQ Test

This is an IQ test given to job applicants in Japan. 

Beside a river there is:

  • Father
  • Son 1
  • Son 2
  • Mother
  • Daughter 1
  • Daughter 2
  • Policeman
  • Thief
"Everybody has to cross the river"

The following rules apply:

  1. Only 2 people on the raft at a time.
  2. The Father cannot stay with any of the daughters, without their Mother's presence.
  3. The Mother cannot stay with any of the sons, without their Father's presence
  4. The thief cannot stay with any family member, if the Policeman is not there.
  5. Only the Father, the Mother and the Policeman know how to operate the raft.

 

Play it online here:

Solution below

 

 

 


 

Hint: Solution can be done in 17 moves. 

 

 

 

 

 

 

 

Solution:

  1. Cop & Thief    -->
  2. <--    Cop
  3. Cop & Son 1     -->
  4. <--    Cop & Thief
  5. Father & Son 1    -->
  6. <--    Father
  7. Father & Son 2    -->
  8. <--    Father
  9. Father & Mother -->
  10. <--    Mother
  11. Cop & Thief    -->
  12. <--    Father
  13. Father & Mother -->
  14. <--    Mother
  15. Mother & Daughter 1 -->
  16. <--    Mother
  17. Mother & Daughter 2 -->

 

 

Difficulty
  • Moderate
Type
  • Logic
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Comments

That doesn't make sense because the father's with daughter one without the mother when the mother goes back for daughter two!
- (7 Jun 2011)

The answer is actually incorrect. If you play the game and try it exactly that way, it does not work.
This is the beginning of your answer:
Cop & Thief -->
<-- Cop
Cop & Son 1 -->
<-- Cop & Thief
Father & Son 1 -->
<-- Father
Father & Son 2 -->
<-- Father
Father & Mother -->
<-- Mother
Cop & Thief -->
<-- Father
Father & Mother -->
<-- Mother
Mother & Daughter 1 -->
((This is where your answer fails. If you bring the mother back, the father is left alone with the first daughter. It does not work this way. In order for the 2nd daughter to make it across, the rest needs to work like this:))
<-- Cop & Thief
Cop & Daughter 2 -->
<-- Cop
Cop & Thief -->
Now you have brought them all safely across the river! It was a good try, though. And the game was quite fun. Thanks(:
- Tessa (7 Jul 2011)

Steps #5 and #6 are unnecessary since son#1 is already on the other side due to the cop
- Bre (9 Jul 2011)

1. Policeman & Prisoner
2. Policeman
3. Policeman & Son 1
4. Policeman & Prisoner
5. Father & Son 2
6. Father
7. Father & Mother
8. Mother
9. Policeman & Prisoner
10. Father
11. Father & Mother
12. Mother
13. Mother & Daughter 1
14. Policeman & Prisoner
15. Policeman & Daughter 2
16. Policeman
17. Policeman & Prisoner
- b0rsuk (3 Apr 2012)

Here is a shorter way to solve it. Is the mother allowed to go over there where sons and no father are as long as she's just feeying over a daughter?

1. Policeman and thief go over
2. policeman comes back
3. police and father go over
4. father comes back
5. father and son1 go over
6. father comes back
7. father and son2 go over
8, father goes back
9. Mother and D1 go over
10. Mother comes back
11. Mother and D2 go over
12. Mother comes back
13. Mother and father go over
- Elena (3 Oct 2012)

in step 3 when father goes other side, mother is left with sons
- (24 Jun 2013)

in step 3 how can father leave son in the presence of mother? it is against rule; it is just brain teaser and no comments pl.

- sastryar (12 Aug 2013)

B0rsuk is the only one right
- (11 Oct 2013)

1.mother and D1 go over.2.mother comes back 3.mother and D2 go over 4.mother comes back 5.mother and father go over 6.father comes back. 7.cop and thief go over. 8.mother comes back 9.father and son1 go over.10.father comes back.11.father and son2 go over.12.father comes back.13.father and mother go over
- Rahul (23 Oct 2013)

A) 2=mother+daughter1. B) 1= mother. C) 2=mother+daughter2. D) 1=mother. E) 2=father+son1. F) 1=father. G) 2=father+son2. H) 1=father. Policeman said, I will tie a rope on the raft to pull it back! Father and mother said, that's smart....since 3 adults can't be left alone! I) 2=father+mother. J) 0=0. K) 2=policeman+thief. Lol...lol...lol...
- mystery (2 Nov 2013)

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