So few commenters are thinking about the distribution - they are all getting hung up on the algebra and what 'x' might be etc. But if you think about the distribution you realise the whole problem is broken. It is not possible for x & 2x (or x/2 for that matter) to have equal probability because for a uniform probability distribution there has to be a maximum amount, after which the probability will be 0.
So few commenters are thinking about the distribution - they are all getting hung up on the algebra and what 'x' might be etc. But if you think about the distribution you realise the whole problem is broken. It is not possible for x & 2x (or x/2 for that matter) to have equal probability because for a uniform probability distribution there has to be a maximum amount, after which the probability will be 0.