P(r is chosen)

correct

 

A basic review of probability.

 

There is a severe problem with probability.

Probability, says nothing about any given event (x) happening, or not happening. It is only the CHANCE that it will, or will not.

For example.

I might have a 99 percent chance x will happen, yet it does not.

I might have a 1 percent chance x will happen, and it does.

Theoretically I can even have 100 percent chance x happens, and it does not. (consider the weather).

Theoretically I can have 0 percent chance x happens, and it does.

In this last cast consider the question. "What is the chance I am going to die today?". A doctor looks at me, tells me I am perfectly healthy. Yet on my way home I am struck by lightning.

Probability is a flawed concept. In the same way as measuring in the quantum world is a flawed concept.

 

The question is not asking you if there is a flaw with probability. Stay on the topic at hand. You want to convert an easy probability question to a distance between two unknown planets. Jesus!!!