Upgrading from:

Statistics`ContinuousDistributions`

Distributions defined in this package have been added to the built-in Mathematica kernel.
The input syntax for UniformDistribution has changed.
Random and RandomArray are replaced by RandomReal.

Continuous distributions are now part of the built‐in Mathematica kernel:

Version 5.2 << Statistics`ContinuousDistributions`; Mean[BetaDistribution[\[Alpha], \[Beta]]]

UniformDistribution is now parameterized by a pair of real endpoints {min,max}:

Version 5.2 Mean[UniformDistribution[min, max]]

Random elements for continuous distributions are generated via RandomReal:

Version 5.2 Random[GammaDistribution[1, 1.5]]
Version 5.2 RandomArray[GammaDistribution[1, 1.5], 5]