Aphid opened the ticket and wrote:

Try out the following code.

function MyScript::ProbCheck(p,k,n){
local r = 0;
local v = 0;
while(r<n)
{
if(GSBase.Chance(p,k))
v++;
r++;
}
GSLog.Info("Sum result:" + (v.tofloat() / n.tofloat() * 100.0) + " percent");
}

I used a while(true) loop like this:

while(true)
ProbCheck(300000, 1000000, 10000);

Results are around 4%. Note: The chance of getting a result of 4% or less is 3.27270834148310^-969
The chance of this happening 100 times in a row is 3.27270834148310^-96900. I do believe there is an error here.

Reported version: 1.3.0
Operating system: All

This issue was imported from FlySpray: https://bugs.openttd.org/task/5517