blob kind of distribution where most of the mass is in the middle but it can actually go all the way to infinity on both sides there's something called standard deviation Sigma and 68% of the mass lies within one standard deviation of the mean and then it kind of decays out from there the mean is usually denoted by mu sanitation by Sigma and then the variance is Sigma squared the density itself is this thing over here so it's exponentiated negative x minus mu square so let's think about that when X is close to MU and the X is equal to