I'll betcha that you could show me the math involved in calculating this, though, and I'd enjoy seeing it.

Seriously? I definitely could, but I'd need to know all the variables (such as how big each playlist is - if we're trying to calculate the actual probability of getting 3 out of 4 tracks all from the same playlist, we need to know how big every playlist is - it's much more likely to happen with a 100 track playlist than, say, a 2 track playlist). It'd be a big, messy calculation.

More generally, though, if we want to just pick 3 particular tracks out of N tracks on the player, and say how likely it is that we see those 3 tracks in a given random set of 4, the calculation is much easier:

(N-3)/N * 3/(N-1) * 2/(N-2) * 1/(N-3) +
3/N * (N-3)/(N-1) * 2/(N-2) * 1/(N-3) +
3/N * 2/(N-1) * (N-3)/(N-2) * 1/(N-3) +
3/N * 2/(N-1) * 1/(N-2)

If N is your aforementioned 1449 tracks, this gives us a probability of about 7.9x10^-9, or 1 in 126501081. Very improbable. :)

But of course, doing the calculation for playlists is very different, and adds all sorts of correlations which aren't there if we choose 3 random tracks and then 4 random tracks, and see if our 3 are contained in our 4.




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Daniel M. Zimmerman
Mk.2 #060000058, 36GB, Red
Mk.1 #00101, 10GB, Blue