  Results of a phenomenological model to estimate the GRB detection rate by the
Fermi Gamma ray Space Telescope are reported. This estimate is based on the
BATSE 4B GRB fluence distribution, the mean ratio of fluences measured at 100
MeV - 5 GeV with EGRET and at 20 keV - 2 MeV with BATSE, and the mean EGRET GRB
spectrum for the 5 EGRET spark-chamber GRBs. For a 10% fluence ratio and a
number spectral index alpha_1 = -2 at 100 MeV - 5 GeV energies, we estimate a
rate of ~ 20 and 4 GRBs per yr in the Fermi Large Area Telescope field of view
with at least 5 photons with energy E > 100 MeV and E > 1 GeV, respectively. We
also estimate ~ 1.5 GRBs per yr in the Fermi FoV where at least 1 photon with
energy E > 10 GeV is detected. For these parameters, we estimate = 1 - 2 GRBs
per year detected with the Fermi telescope with more than 100 gamma rays with E
>~ 100$ MeV. Comparison predictions for alpha_1 = -2.2, different fluence
ratios, and the AGILE gamma-ray satellite are made. Searches for different
classes of GRBs using a diagram plotting 100 MeV - 10 GeV fluence vs. 20 keV -
20 MeV fluence is considered as a way to search for separate classes of GRBs
and, specifically, spectral differences between the short-hard and long
duration GRB classes, and for hard components in GRBs.
