  The coordinate of a harmonic oscillator is measured at a time chosen at
random among three equiprobable instants: now, after one third of the period,
or after two thirds. The (total) probability that the outcome is positive
depends on the state of the oscillator. In the classical case the probability
varies between 1/3 and 2/3, but in the quantum case -- between 0.29 and 0.71.
