Find the probability whose odds against are given in the problem.

Odds against are 10000 to 1

I'm not sure what you are seeking.

If the odds against are 10,000 to 1, then the odds of success are 1 in 10,000.

PsyDAG is wrong, I believe.

The odds are 1/(10,000+1) or 1/10,001.

To find the probability when the odds against are given, we can use the formula:

Probability = 1 / (odds against + 1)

In this case, the odds against are given as 10000 to 1. To find the probability, we substitute this value into the formula:

Probability = 1 / (10000 + 1)
Probability = 1 / 10001

Therefore, the probability is 1/10001.