  In 1964 Lochs proved a theorem on the number of continued fraction digits of
a real number $x$ that can be determined from just knowing its first $n$
decimal digits. In 2001 this result was generalised to a dynamical systems
setting by Dajani and Fieldsteel, where it compares sizes of cylinder sets for
different transformations. In this article we prove a version of Lochs' Theorem
for random dynamical systems as well as a corresponding Central Limit Theorem.
The main ingredient for the proof is an estimate on the asymptotic size of the
cylinder sets of the random system in terms of the fiber entropy. To compute
this entropy we provide a random version of Rokhlin's formula for entropy.

Dynamical Systems