What is Exponential Distribution formula?

Exponential Distribution Formula

The continuous random variable, say X is said to have an exponential distribution, if it has the following probability density function:

fx( x|λ ) = λe^(λ x), for x>0
          = 0, for x<=0


λ is called the distribution rate.

The value lambda represents the mean number of events that occur in an interval. The x represents the moment that the event will occur. Thereby, when the average occurrence of the events is lambda, f(x, lambda) gives the probability of occurrence of the event at the moment x.