Reasoning Skills Brain Teaser

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Puz­zle:

Marie, Claude, and Jean are in a com­pe­ti­tion. Here are their results:

  1. The youngest per­son received the least points.
  2. Claude got half of the points of the eldest.
  3. Jean received as many points as both oth­ers combined.

Ques­tion:
Who is the eldest ?

The Brain Exercise:
This puz­zle uses plan­ning and rea­son­ing skills. You read the state­ments and then must devel­op a plan to solve the prob­lem using your rea­son­ing skills. These skills are found pre­dom­i­nant­ly in your pre­frontal cor­tex. This area of your brain is respon­si­ble for exec­u­tive func­tions such as plan­ning, struc­tur­ing, and eval­u­at­ing vol­un­tary, goal-direct­ed behav­ior, i.e., activ­i­ties requir­ing the con­stant com­par­i­son of planned acts with the effects achieved.

If you’ve already got the puz­zle fig­ured out, click on the link below to find the answer.

Solu­tion:
Start with state­ment #2 which tells us that Claude is not the eldest. So the eldest must be either Marie or Jean. State­ment #3 tells us that Jean received the sum of the oth­er two peo­ple’s points, and those point totals are not equal, per state­ment #1 (the youngest has less points than the oth­er two). For Jean to be the eldest, Claude and Marie would each have half of the points of Jean has, but we know they can’t have the same amount of points. There­fore, Jean must have the most points, and Claude must be the youngest, but Marie is the eldest.

Reader Interactions

Comments

  1. joseph benedict says

    this does not make sense.. 

    If the youngest per­son has least points
    jean has the sum of equal points of the oth­er two.. (claude has 1/2)
    then, no per­son could be the youngest and jean would be eldest by com­mon sense.

    hon­est­ly who made this??

  2. Caroline says

    The puz­zle says that Jean has as many points as the oth­er two peo­ple com­bined, and those points are not equal giv­en that the youngest per­son has the least amount of points.

    Try it with Jean as the eldest. Say Jean has 10 points, then Claude must have 5 points, leav­ing Marie with 5 points. Then, there is no least amount of points and there­fore, no youngest.

    But what if Jean got the most points, Marie was the eldest, and Claude got half of Marie’s points? Then it works. Say Marie got 10 points, then Claude got 5 points, and Jean got 15 points.

    The eldest did not have to get the most points.

    It’s tricky and tests your auto­mat­ed assumptions!

  3. Coen says

    great fun! Nobody said that the com­pe­ti­tion was about points. Good reminder to read close.

  6. Alvaro says

    Hel­lo Jazz,

    I was start­ing to write an answer but I can­not real­ly improve Caroline’s…

    Let’s start with “Claude got half of the points of the eldest.”

    Giv­en this, it is clear Claude is not the eldest. The 2 options now are Marie and Jean.

    Now, to make things eas­i­er, why don’t you get pen & paper and imag­ine 2 sce­nar­ios, one with Jean as eldest, one with Marie as eldest? give real num­bers. You will see that Jean can­not be the eldest and yet ful­fill those 3 con­straints, there­fore the only answer can be Marie.

    In any case, the real point here is to try!

  7. Beck says

    For fur­ther expla­na­tion, let’s revert back from the solu­tion and rephrase the 3 results.

    From most points to least:
    — Jean = 2x + x
    — Marie (eldest) = 2x
    — Claude (youngest) = x 

    - Based on the results as indi­cat­ed by the puz­zle, both results 1 and 2 point to Claude; there­fore it can be com­bined and rephrased as:
    “Claude is the youngest per­son with the least amount of points, which was half the amount of points of the eldest.”

    Inter­est­ing web­site BTW. =)

  8. Beck says

    For­got to rephrase the 3rd result:
    “Jean received as many points as both Marie and Claude combined”

    I sus­pect some peo­ple may false­ly asso­ciate the eldest with the most points to begin with, which may com­pli­cate the puzzle.

  9. Patkuta says

    “Jean received as many points as both oth­ers combined.”

    While to some, this sen­tence might imply:
    j = c + m
    (where the vari­able rep­re­sents the num­ber of points of the respec­tive person)

    To me, all says is:

    j >= m + c

    In which case, both Marie and Jean could be the eldest:
    youngest: Marie with 1 point
    mid­dle: Claude with 2 points
    eldest: Jean with 4 points

    So either: I can’t under­stand Eng­lish prop­er­ly, there are two answers, or premise 3 is too ambiguous.

  10. Gi says

    I’m dis­ap­point­ed in the edu­ca­tion­al sys­tem! Great puz­zle. There is only ONE answer!

  12. anonymous says

    It should be spec­i­fied that “least” and “eldest” means *strict inequality*.

    Oth­er­wise, j=c=m=0 is a solu­tion, which does­n’t reveal infor­ma­tion about age.

  18. RUdumb? says

    It’s Jean.
    j=c+m
    nobody says that there was a set amount of point for these three people..so M can have any points in between C and J.
    If M is the eldest ‘x’ points C has ‘x/2’ points so J has(j=m+c) x+ x/2 so Jean has more .. he is the eldest…

  19. magaru says

    Claude and Marie can have the same age .
    In that case she can have the same points as Claude and phare 2 is still true.

  20. lee says

    I see. Marie is def­i­nite­ly the eldest. It does­n’t say the eldest gets the most points. See if Claude gets half the points of the eldest, and marie is the eldest, Jean can have as much as both of them, exam­ple claude — 20, marie, 40, jean 60. jean = marie + claude, Claude = 20 = Youngest. Jean = 60 = Not old­est, but most points, Marie = 40 = 2x Claude = Eldest.

  21. Steve says

    I dont see any pos­si­ble solu­tion that fits all the variables. 

    Yes Jean would log­i­cal­ly be the elder:
    “Jean received as many points as both oth­ers combined”

    but if Claude’s points were half of Jeans”
    “Claude got half of the points of the eldest”

    Then Marie had to have the same num­ber of points as Claude so the first line isn’t true:
    “The youngest per­son received the least points”

  22. loreto says

    it took time to real­ize but marie is def­i­nite­ly the old­est. lets say score was 105. c got half of the old­est. j got both com­bined. c=35. m=70. 35+70=(j)105