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2.4.1 Exponential Distribution

This distribution can describe a number of physical phenomena, such as the time t for a radioactive nucleus to decay, or the time x for a component to fail, or the distance z a photon travels in the atmosphere before suffering a collision with a water molecule. The exponential distribution is characterized by the single parameter , and one can easily show that the mean and variance for the exponential distribution are given by:

Figure 6 illustrates the exponential distribution. Note that the standard deviation of the exponential distribution is