  Simple interpolation formulas are proposed for the description of the
renormalization group (RG) scale dependences of the gravitational couplings in
the framework of the 2-parameters Einstein-Hilbert (EH) theory of gravity and
applied to a simple, analytically solvable, spatially homogeneous and
isotropic, spatially flat model universe. The analytical solution is found in
two schemes incorporating different methods of the determination of the
conversion rule $k(t)$ of the RG scale $k$ to the cosmological time $t$. In the
case of the discussed model these schemes turn out to yield identical
cosmological evolution. Explicit analytical formulas are found for the
conversion rule $k(t)$ as well as for the characteristic time scales $t_G$ and
$t_\Lambda>t_G$ corresponding to the dynamical energy scales $k_G$ and
$k_\Lambda$, respectively, arising form the RG analysis of the EH theory. It is
shown that there exists a model-dependent time scale $t_d$ ($t_G\le
t_d<t_\Lambda$) at which the accelerating expansion changes to the decelerating
one. It is shown that the evolution runs from a well-identified cosmological
fixed point to another one. As a by-product we show that the entropy of the
system decreases monotonically in the interval $0<t\le t_\Lambda$ due to the
quantum effects.
