Later we will learn that we can associate the standard deviation with a sort of
expected deviation from the mean, meaning that for the exponential
distribution, one would expect most samples **x** to fall within of
, even though
the actual range of samples **x** is infinite.
One can see this by computing the probability that a sample from the
exponential distribution falls within of
the mean

Hence 83% of the samples from the exponential distribution can be expected to fall within a half of a standard deviation of the mean, although some of the samples will be far from the mean, since .

Figure 6: Exponential pdf.