  We show that if the intrinsic break energy of Gamma-Ray Bursts (GRBs) is
determined by the product of more than three random variables the observed
break energy distribution becomes almost lognormal including the redshift
effect because of the central limit theorem. The excess from the lognormal
distribution at the low break energy is possibly due to the high redshift GRBs.
The same argument may also apply to the pulse duration, the interval between
pulses and so on.
