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DIY Challenge 2: Fastest 3 horses

There are 15 horses and five lanes on a race track.

What would be your strategy to find the fastest 3 horses?

What students worked out11

  • Student 3

    first 3 races
    say a5a4a3a2a1, b5b4b3b2b1, c5c4c3c2c1
    and results as in attachment then a5,a4,b5,b4,c5,c4 horses are out in first 3 races

    • Student 3

      now race 4
      between a1b1c1
      say b1 is winner
      then a3 and c3 are out of race

      • Student 3

        race 5
        between a1,b2 and c1 horse
        say b2 wins race
        so by now b1 is fastest, b2 is second fastest
        after this race a2 and c2 are out of race

        • Student 3

          last race
          race 6
          for deciding third position
          a1b3and c1

  • Student 3

    last race
    race 6
    for deciding third position
    a1b3and c1

  • Student 2

    first, do 3 races
    row 1
    row 2
    row 3
    the last 2 in all races are eliminated
    then we are left with 9
    we race any 5
    last 2 eliminated
    7 left
    then we race 5
    last 2 eliminated
    5 left
    then we race those 5
    last 2 eliminated
    the 3 left 1/2/3 this is the order these are the 3 fastest

    • Student 2

      total of 6 races

  • Student 1

    You run 3 groups of 5 separately then out of each run you take out the top three after each race. Now you’ve selected 9 horses.
    Assume –
    Top 3 horses from top row of 5 are -A 1’st B 2’nd C 3’rd (In that order)
    Top 3 horses from middle row of 5 are -D E F (In that order)
    Top 3 horses from top row of 5 are -G H I (In that order)

    Depending on which 3 horses are in the top three there are different possibilities of what will happen I’ve written on

    Then we race top horse from each of the 3 rows and 2 horses that came 2’nd – A D G B E.
    let’s say that D E A won if A came first D and E need to race B and C two horses will lose and you’ve got the top three.
    Say A comes second and D comes first A and C have to race against B C F then three will get eliminated and 2 will win
    Say A came last hea has to race against F if he wins then the fastest horses are A D E if not D E F

    • Student 1

      You run 3 groups of 5 separately then out of each run you take out the top three after each race. Now you’ve selected 9 horses.
      Assume –
      Top 3 horses from top row of 5 are -A 1’st B 2’nd C 3’rd (In that order)
      Top 3 horses from middle row of 5 are -D E F (In that order)
      Top 3 horses from top row of 5 are -G H I (In that order)

      Then we race top horse from each of the 3 rows and 2 horses that came 2’nd – A D G B E.

      Depending on which 3 horses are in the top three there are different possibilities of what will happen. I’ve written one-

      Let’s say that D E A won. If A came first or second then A,D and E are the fastest. Because if B is eliminated then C is also eliminated and also if G is eliminated then so is H and I. F is also out because it is slower than E and A is faster than E.
      Say A came third he has to race against F if he wins then the fastest horses are A D E if not D E F.

      • Student 1

        If A D G are the three top most then B C and E F are eliminated. If G is third then H and I are eliminated and the three top most are A D G. In the case that G is first the A and D have to race H and I then two will be eliminated. if G comes 2nd and D comes 1’st A has to race H and I two will be eliminated an there is a winner same case if A comes 1’st only difference is that D has to race H and I.

        • Student 1

          With my strategy we only need 3 races at the max and two if lucky