It probably goes down the list of planets and checks each in decending order, instead of randomly picking from the list.



Hehe, yea. Run worldSST and track busts by day on the ct. Some useful info there.

ok, so i did this brute force. given 15 planets, there are 105 possible unique pairings of planets that can collide. out of those 105 pairs, 14 of the pairs contain one particular planet. so the probability of colliding that planet is 14/105, which happens to equal 1/14 + 1/15 - 1/(14*15), or 13.33%. so my original equation was close to right.

If you treat it as a conditional, yes.

Let's work thru with a smaller number of planets, say 5.
1-2, 1-3, 1-4, 1-5
2-1, 2-3, 2-4, 2-5
3-1, 3-2, 3-4, 3-5
4-1, 4-2, 4-3, 4-5
5-1, 5-2, 5-3, 5-4

Or 20 pairings w/ duplicates. W/o duplicates:
1-2, 1-3, 1-4, 1-5
2-3, 2-4, 2-5
3-4, 3-5
4-5

10 pairs. There's an equation for this to make it easy:
n! / k!(n-k)!

Where n is the number of elements and k is the size of each set. So...
5! / 2!*3! = 120 / 2*6 = 120/12 = 10

If you had planet #1, there would be 4 sets. Planet #2, same, 3, same, etc.

In otherwords for a set of N elements, there exist N-1 sets that contain it.

In otherwords for a set of N elements with K sized pairs, you have...

probability = (n-1) / [n! / k!(n-k)!]

So if k=2 (looking for pairs) we have:

(n-1) / [n! / 2(n-2)!]

Invert and multiply...

probability = 2*(n-1)*[(n-2)!] / n!

So for 15 planets...

2*14*13! / 15!

Since 15! = 15 * 14 * 13! We have...

2*14 / 15*14

14 cancels and gives us 2/15 or 13.3%.

Which if you look back to my first post in the thread is exactly what I said.

But if all you want to know is what the odds of your planet colliding are on each selection, it's 1/15, then 1/14. Ie: If you don't want the conditional.

Yep, that was my thought. The question is...how would that change the odds?



As many people that have played the game over the years, how many do you think bothered to actually check it out?

With some preplanning you could probably make sure the overload planets are the lower numbered planets improving you odds of taking out a vital planet.

I tried attaching an Excel collision calculator but got a message saying file type .XLS not allowed? Any suggestions?

That seemed to to it SG, thanks!

Here's an Excel collision calculator. Note however that since TW seems to check collisions for the higher numbered planets first, it may not be 100% accurate. Still it should be close enough, at least until someone figures out exactly how TW checks for collisions...

just fyi, the forum probably defaults to not allow xls uploads because they can and often do carry malicious vb script code.