Who knows where we got this data from, that the average man drinks 2 liters, and that the standard deviation is this. Maybe there's some huge study, and this was the best estimate of what the population parameters are, that this is the mean and this is the standard deviation. Now we're sampling 50 men. And what we need to do is figure out, essentially, what is the probability that the mean of this sample, that the sample mean is going to be greater than 2.2 liters. And to do that, we have to figure out the distribution of the sampling mean. And we know what that's called. It's the sampling distribution of the sample means.