4. Marbles
4.1 Introduction
These methods use a set of objects, the randomness is given by the odd
of picking one object of a given kind.
4.2 Sixteen marbles (copied from
Clarity)
- Materials
- 16 marbles in four colours:
- Five of the first colour, which represent the line
- Seven of the second colour, which represent the line
- Three of the third colour, which represents the line
- One of the fourth colour, which represents the line
- Usage
- Put all the marbles in a bag or bowl, and draw one out at
random to select the line. After each line, replace the marble in the
receptacle.
- Comment
- This is the easiest way of emulating
yarrow stalks' odds.
Prob(
) = 1/16 = 0.0625
Prob(
) = 7/16 = 0.4375
Prob(
) = 5/16 = 0.3125
Prob(
) = 3/16 = 0.1875
Prob(
or ) =
8/16 = 0.5
Prob(
or )
= 8/16 = 0.5
Prob(
->
) = 1/8 = 0.125
Prob(
->
) = 3/8 = 0.375
The outcome are the same up to far less than 1/100 (look at the comparison
table)
|
Marbles |
Yarrows |
Coins |
|
0.0625 |
0.0663 |
0.125 |
|
0.3125 |
0.3163 |
0.375 |
|
0.4375 |
0.4337 |
0.375 |
|
0.1875 |
0.1837 |
0.125 |
- Variation
-
4.3 Ten marbles (thanks to Dee)
- Materials
- 10 marbles in four colours:
- Four of the first colour, which represent the line
- Four of the second colour, which represent the line
- One of the third colour, which represents the line
- One of the fourth colour, which represents the line
- Usage
- Put all the marbles in a bag or bowl, and draw one out at
random to select the line. After each line, replace the marble in the
receptacle.
- Comment
-
Prob(
) = 1/10 = 0.1
Prob(
) = 4/10 = 0.4
Prob(
) = 4/10 = 0.4
Prob(
) = 1/10 = 0.1
Prob(
or ) =
5/10 = 0.2
Prob(
or )
= 5/10 = 0.5
Prob(
->
) = 1/5 = 0.2
Prob(
->
) = 1/5 = 0.2
This method is symmetric as the three coins
one, but give less moving line (chance 10% instead of 12.5%).
|