In Sp's original problem, he asked that the outcomes be random in the sense
of being equally likely to occur over the triangle with vertices 100, 010, 001,
This might be a paraphrase of the current problem: suppose you have a way
to generate equally likely outcomes of a single variable, say of x, in the interval [0,1].
How might you use that to create outcomes that are equally spaced over the triangle?
That is, not clustered near, for example, the vertices, or near the center, etc.
For the triangle, there are a number of "obvious" approaches that don't give
a uniform distribution.
If that's not what being asked, it's still an interesting exercise; it finds use in simulations
where probability is not easily calculated; but by repeating a random outcome
many times, and counting the desired results as a fraction of the total of the trials,
the probability emerges.
Hint for plasmid:
Since we want uniformity over a plane surface, this should be achievable using only
two applications of a one-dimensional random number generator.