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Misunderstanding Randomness

Age 11 to 14
Challenge Level Yellow starYellow star
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Patrick from Woodbridge School sent us the following comments:

My definition of "random" that I use here is "involving equal chances for each number".

In fact, mathematicians use the word 'random' to mean something happens, or is chosen, by chance, and not by a rule or a pattern.
When does this agree/disagree with Patrick's comments?

I believe that:

a) This is not random, as clearly the number 2 has a far higher chance of coming up.

b) This is not a mistake - the chances are 1/(2^10) that this could happen, so it is unlikely but perfectly possible

c) This is not true - there is still a 1/2 chance of this happening, the coin is not conscious.

d) This is possible but not true - again, there is a chance (albeit quite small) that this could happen.

e) This is possible but we only have a small sample of the number so it could repeat after 16 decimals, for example.

f) This is true - if there is no pattern to the digits.

g) This is very nearly but not quite random - it is influenced by some environmental factors (an extreme example is growing up with a heavy weight on your head!).

h) i) This is not necessarily true - the rain might still happen but might cover the whole region.
ii) This is not true - there might be huge downpours all the time, that were unexpected, to generate the 30% chance.
iii) This is true assuming the weather behaves, and the weather forecaster has given out the same warning.
iv) This is a slightly odd way of making the statistic, but it could be used.

i) The weather is not totally random - for example, a drop in air pressure is linked to thunderstorms.

j) This is partially true - some remnants of the weather will affect the weather for tomorrow.

k) This is wrong - the balls are totally random. There is the same chance of winning withballs of one colour as winning with balls of varied colours.

l) This is wrong - it is almost impossible to choose any correct sequence. There is no more likelihood of the sequence being 1, 2, 3, 4, 5, 6 than 11, 24, 28, 34, 41, 45.

m) Chris is right - Anna is right using my definition, but Bob is right using a definition of "allowing equal chances of all digits".

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The NRICH Project aims to enrich the mathematical experiences of all learners. To support this aim, members of the NRICH team work in a wide range of capacities, including providing professional development for teachers wishing to embed rich mathematical tasks into everyday classroom practice.

NRICH is part of the family of activities in the Millennium Mathematics Project.

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