You used some formula to calculate the probability from your data. Your data has an uncertainty. Therefore, by propogation of uncertainty, your probability has an uncertainty. That is, you use the technique of propagation of uncertainty to find the uncertainty.
If your first year, check this out:
Thank you, I read the pdf, and I found it useful, but I did not find the answer to my question. I didn't use a formula to calculate the probability, I just observed that I got this outcome 43 out of 234 times