I am not the greatest statistician (trying to get better), and I also play a bit of disc golf on the same course that is by my house.

I want to lower my score, and in order to do that I have to practice the holes that I am worst on, so I figure that the holes with the highest mean, and the holes with the greatest standard deviation are the ones I should focus on.

The mean is pretty easy, I just add up all my games and divide by the total, but how do I find the standard deviation?? Does there have to be an underlying distribution? Do I have to know the probability of getting any singular score?