Puzzles with numbers and things

[snookersfun]

So, here is the next round. According to the new rules, I shall have the answers PMed as well. Deadline is until Wednesday 12:00 pm (d_g's time).

Assume that there is a big sack with an equal number each of several colored snooker balls (there might be more than the traditional 6 colors though- I am just madly trying to relate this thing to snooker). Now, if one adds 20 balls of a new color to this mix, one wouldn't change the probability of picking two balls of the same color from the bag. (This is w.o. returning the balls after the picks).
The question is how many balls were in the sack, before those balls were added?

[snookersfun]

can I ask another one meanwhile? I have no more good fractions for the above one...

[davis_greatest]

Ok, I'll go for 1/5 then.

Still no right answers... sorry

[abextra]

Ok, I'll go for 1/5 then.

[davis_greatest]

1/4
not that you think, I am just guessing (there is some serious thinking behind this all, just the theory evades me....)

It's not 1/4 either This question is lasting much longer than I had thought it would!

[snookersfun]

1/4
not that you think, I am just guessing (there is some serious thinking behind this all, just the theory evades me....)

[davis_greatest]

or wait 1/6 sounds good as well.

Many of those fractions sound good... but none sounds good enough!

[snookersfun]

or wait 1/6 sounds good as well.

[snookersfun]

is that a trick question and finally it is 1/3?????

[davis_greatest]

I went for something like 1/9^n (for n = number of completed exchanges),
but this is probability and 'ichs'

It's bigger than 1/9.

[snookersfun]

I went for something like 1/9^n (for n = number of completed exchanges),
but this is probability and 'ichs'

[davis_greatest]

in that case is it really small (tiny fraction)?

Um.... well, what do you class as tiny? I wouldn't call it THAT small...

[snookersfun]

in that case is it really small (tiny fraction)?

[davis_greatest]

No correct answers yet. Not elvaago's 1/9, nor snookersfun's 2/9...

[snookersfun]

why not 2/9? But I am really bad at this kind of stuff?