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st: mean of a distribution


From   carol white <wht_crl@yahoo.com>
To   statalist@hsphsun2.harvard.edu
Subject   st: mean of a distribution
Date   Sun, 18 Oct 2009 11:05:05 -0700 (PDT)

Hi,
How to calculate the mean of the distribution of a random variable? Take the exponential distribution with the probability density function f(x)=lambda.exp(-lambda.x) where lambda is a constant and x is a random variable. The mean of this distribution is the reciprocal of lambda. If the mean is the expected value of x, which for a continuous random variable E(x) = Integral (x.f(x))dx, how could E(x) be the reciprocal of lambda?

Regards,

Carol 


      
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