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Maths gurus


Grant

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Of helping me out out here?

Trying to help my girlfriend with her uni work but the days of maths were oh so long ago.

Scenario:

You have 100 balls and drop them randomly amongst five urns.

What is the probablity of

a) 20, 20, 20, 20, 20

b) 18, 19, 20, 21, 22

Each number above represents the number of balls in each urn. N factorial is popping into my head for some reason but I really just can't remember what to do.

Help is much appreciated!

Grant

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  • Gandalf the Grey, Maiar of Manwë and Varda, Team HgAg/Sneaky
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We'll have to summon Ken :ermm: for this one Grant... :ermm:

If you say his name, he will appear. :nod:

... now ... 2+2=22 right? :huh:

:k24t:

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  • Toughest BA Turbo
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It’s been 30 years since combinatorial probability at Uni, so here goes my stab:

1. (4!/(5**4)) ** 20 = (24/625) ** 20

the alternative way is

1 * ((4/5) **20) * ((3/5) **20) * ((2/5) ** 20) * ((1/5) ** 20)

giving the same answer both ways

2. ((4!/(5**4))**18) * ((4 * 3**2 * 2**3) / (5**20)

I could be completely wrong, as those brain cells may no longer exist.

Brian

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  • FORD FORD FORD
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Um, get a GF that has finished Uni, does that help?

Scotty

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  • Gandalf the Grey, Maiar of Manwë and Varda, Team HgAg/Sneaky
  • Member
  • Member For: 21y 6m 15d
  • Gender: Male
  • Location: The Shire, Middle Earth
It’s been 30 years since combinatorial probability at Uni, so here goes my stab:

1. (4!/(5**4)) ** 20 = (24/625) ** 20

the alternative way is

1 * ((4/5) **20) * ((3/5) **20) * ((2/5) ** 20) * ((1/5) ** 20)

giving the same answer both ways

2. ((4!/(5**4))**18) * ((4 * 3**2 * 2**3) / (5**20)

I could be completely wrong, as those brain cells may no longer exist.

Brian

You continue to amaze me Brian ... :censored:

:blush:

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