  The exact solution of a two-scale Buchert average of the Einstein equations
is derived for an inhomogeneous universe which represents a close approximation
to the observed universe. The two scales represent voids, and the bubble walls
surrounding them within which clusters of galaxies are located. As described
elsewhere [gr-qc/0702082], apparent cosmic acceleration can be recognised as a
consequence of quasilocal gravitational energy gradients between observers in
bound systems and the volume average position in freely expanding space. With
this interpretation, the new solution presented here replaces the Friedmann
solutions, in representing the average evolution of a matter-dominated universe
without exotic dark energy, while being observationally viable.
