Boat

Written on 7:52 am by Vja Students

A family of five ( Father, Mother, Lisa, Brad, and Emily) each have a dog of their own. They need to cross the river but have a severe problem. There is a boat which holds a maximum of three living things (people or dogs). The dogs are extremely sensitive and CANNOT be left alone with another family member unless their owner is present. NOT EVEN MOMENTARILY. They can left be alone with each other, however. The crossing would be impossible except for the fact that Lisa's dog is trained to drive the boat. How many trips are necessary to get everyone across the river?

Answer: 11 trips

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10 Comments

  1. Unknown | 3 March 2008 at 4:26 pm

    4

     
  2. Unknown | 3 March 2008 at 5:13 pm

    Sorry... its 5

     
  3. Anonymous | 5 March 2008 at 5:56 pm

    i am not able to do it in 5 trips.. its taking more than that... 10 trips
    with one trip being one side of the river to the other....

    that is... one side of the river to the other and back would be 2 trips !

     
  4. Anonymous | 7 March 2008 at 2:04 am

    they are crossing it in 11 steps...
    i dont know if m wrong... but please publish the answer! i have been chking the site everyday since 4th !

     
  5. Fazeetha | 8 March 2008 at 7:28 am

    5 steps.
    first father, mother, emily-1
    next father comes back...2
    father,lisa,dog....3
    lisa and dog come back...4
    brad,lisa and dog goes to the other bank...5

    so 5 steps..

    am i right?

     
  6. Devika Singh | 8 March 2008 at 3:08 pm

    This comment has been removed by the author.

     
  7. Anonymous | 8 March 2008 at 4:39 pm

    11 trips.

    1) Lisa Dog,Father's Dog,Mother's Dog go
    2) Lisa's Dog returns
    3) Lisa's Dog, Lisa go
    4) Lisa returns
    5) Lisa, Father, Mother go
    6) Lisa, Liza's dog return
    7) Lisa, Brother, Emily go
    8) Lisa return
    9) Brother's dog, Emily's dog, Lisa's dog
    10) Lisa's dog returns
    11) Lisa, Lisa's dog go.

     
  8. Anonymous | 9 March 2008 at 1:31 pm

    @devika :: Lisa will not return coz Father's dog and mother's dog are waiting ...[:D]

     
  9. Nits | 9 March 2008 at 5:02 pm

    @Fazeetha
    you forget 4 dogs...
    Another solution with 11 steps...
    1. father's dog, mother's dog, lisa's dog go
    2. lisa's dog returns
    3. Lisa's dog, brad's dog go
    4. Lisa's dog return
    5. father, mother, brad go
    6. brad, brad's dog return
    7. brad, emily,lisa go
    8. lisa returns
    9. lisa, lisa's dog go.
    10. Lisa's dog return.
    11. Lisa's dog, brad's dog, emily's dog go...

    This is the solution...

     
  10. Anonymous | 10 March 2008 at 8:42 am

    Lisa will not go with her dog in 9, coz Brad's and Emily's dog are waiting [:D]

     

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