(1) The form of scientific probability sentences is given unambiguously for the first time by quantum mechanics (form (II); all scientific probability statements can be written in this form. (2) The rules of transformation are also determined by quantum mechanics they agree with the axioms given by Reichenbach (1), p. 118. (3) Frequency interpretation agreeing with the statistical tests used in scientific practice can be given in the frame of truth-semantics at least aa a first approximation.