Skip to content
  • Categories
  • Recent
  • Tags
  • Popular
  • Users
  • Groups
Skins
  • Light
  • Cerulean
  • Cosmo
  • Flatly
  • Journal
  • Litera
  • Lumen
  • Lux
  • Materia
  • Minty
  • Morph
  • Pulse
  • Sandstone
  • Simplex
  • Sketchy
  • Spacelab
  • United
  • Yeti
  • Zephyr
  • Dark
  • Cyborg
  • Darkly
  • Quartz
  • Slate
  • Solar
  • Superhero
  • Vapor

  • Default (No Skin)
  • No Skin
Collapse

The New Coffee Room

  1. TNCR
  2. General Discussion
  3. Puzzle time: the runt of random points

Puzzle time: the runt of random points

Scheduled Pinned Locked Moved General Discussion
11 Posts 3 Posters 54 Views
  • Oldest to Newest
  • Newest to Oldest
  • Most Votes
Reply
  • Reply as topic
Log in to reply
This topic has been deleted. Only users with topic management privileges can see it.
  • HoraceH Offline
    HoraceH Offline
    Horace
    wrote on last edited by Horace
    #2

    :::

    I suppose the number where there's a 50/50 shot of never randomly choosing below it in 10 tries.

    :::

    Education is extremely important.

    jon-nycJ 1 Reply Last reply
    • HoraceH Horace

      :::

      I suppose the number where there's a 50/50 shot of never randomly choosing below it in 10 tries.

      :::

      jon-nycJ Online
      jon-nycJ Online
      jon-nyc
      wrote on last edited by
      #3

      @horace And that number would be?

      "You never know what worse luck your bad luck has saved you from."
      -Cormac McCarthy

      1 Reply Last reply
      • jon-nycJ Online
        jon-nycJ Online
        jon-nyc
        wrote on last edited by
        #4

        Hint:

        :::

        Think circle, not line.

        :::

        "You never know what worse luck your bad luck has saved you from."
        -Cormac McCarthy

        HoraceH 1 Reply Last reply
        • HoraceH Offline
          HoraceH Offline
          Horace
          wrote on last edited by
          #5

          :::

          .5=(1-n)^10

          =0.066967

          :::

          Education is extremely important.

          1 Reply Last reply
          • jon-nycJ jon-nyc

            Hint:

            :::

            Think circle, not line.

            :::

            HoraceH Offline
            HoraceH Offline
            Horace
            wrote on last edited by
            #6

            @jon-nyc said in Puzzle time: the runt of random points:

            Hint:

            :::

            Think circle, not line.

            :::

            Right, my formula would give the median but not the mean. Higher minimums have more room for outliers than lower minimums, which can only go to zero.

            Education is extremely important.

            1 Reply Last reply
            • KlausK Offline
              KlausK Offline
              Klaus
              wrote on last edited by
              #7

              :::

              If you choose 1 number, the average of the mimimum is 0.5.
              With 2 numbers, it's 0.333. With 3 it's 0.25.

              With n numbers it's 1/(n+1), hence for 10 it's 0.909...
              :::

              1 Reply Last reply
              • jon-nycJ Online
                jon-nycJ Online
                jon-nyc
                wrote on last edited by jon-nyc
                #8

                Klaus is right.

                Well, that was my answer. Official solution comes Saturday.

                :::

                One way to think about it is as follows: Pick 11 random points on a unit circumference circle (expected distance between points is 1/11). Randomly pick one as marking start/end point of unit line.

                :::

                "You never know what worse luck your bad luck has saved you from."
                -Cormac McCarthy

                1 Reply Last reply
                • HoraceH Offline
                  HoraceH Offline
                  Horace
                  wrote on last edited by
                  #9

                  I'm sure that's right.

                  Education is extremely important.

                  1 Reply Last reply
                  • jon-nycJ Online
                    jon-nycJ Online
                    jon-nyc
                    wrote on last edited by
                    #10

                    @Horace My original intuition was similar to yours but with a different formula.

                    The probabilities would be additive, not multiplicative, no?

                    So if m is the expected minimum value, that meant that:

                    10 * p(x<m) = 0.5, or
                    p(x<m) = 0.05
                    which gave me 1/20.

                    But as you pointed out that would be a median value, the mean would be higher than that.

                    "You never know what worse luck your bad luck has saved you from."
                    -Cormac McCarthy

                    HoraceH 1 Reply Last reply
                    • jon-nycJ jon-nyc

                      @Horace My original intuition was similar to yours but with a different formula.

                      The probabilities would be additive, not multiplicative, no?

                      So if m is the expected minimum value, that meant that:

                      10 * p(x<m) = 0.5, or
                      p(x<m) = 0.05
                      which gave me 1/20.

                      But as you pointed out that would be a median value, the mean would be higher than that.

                      HoraceH Offline
                      HoraceH Offline
                      Horace
                      wrote on last edited by Horace
                      #11

                      @jon-nyc said in Puzzle time: the runt of random points:

                      @Horace My original intuition was similar to yours but with a different formula.

                      The probabilities would be additive, not multiplicative, no?

                      So if m is the expected minimum value, that meant that:

                      10 * p(x<m) = 0.5, or
                      p(x<m) = 0.05
                      which gave me 1/20.

                      But as you pointed out that would be a median value, the mean would be higher than that.

                      My formula gives the correct median. It's the chance of rolling higher than "x" 10 times in a row, so multiplicative.

                      Education is extremely important.

                      1 Reply Last reply
                      Reply
                      • Reply as topic
                      Log in to reply
                      • Oldest to Newest
                      • Newest to Oldest
                      • Most Votes


                      • Login

                      • Don't have an account? Register

                      • Login or register to search.
                      • First post
                        Last post
                      0
                      • Categories
                      • Recent
                      • Tags
                      • Popular
                      • Users
                      • Groups