
38 Modeling and In verse Problems in the Presence of Uncertainty
By (2.74), (2.93) and (2.94), we find the skewness of the exponentially dis-
tributed random variable is given by
Skew(X) = 2, (2.95)
which is consistent with the left plot of Figure 2.7. In addition, (2.95) indi-
cates that the skewness of the exponentially distributed random variable is
independent of its rate parameter.
The exponential distribution has a number of important properties. Below
we list a few of them, and refer the interested reader to [9, Section 2.1] and [22,
Section 5.6 ] for more informa tion. Let X ∼ Exp(β). Then for any positive
number a we have
aX ∼ Exp(β/a), (2.96) ...