Still disputed answer to a physics quiz question..

I remember a dispute I once had with an instructor over an answer to a physics question about potential energy. It went something like this..

A 10 kg monkey climbs a frictionless tree to a height of 10m and then pulls a 5kg weight up from the ground using a massless rope.  What is the potential energy of the monkey holding onto the weight?

My Answer:  Zero.  A monkey can't climb a frictionless tree.

No credit.  wrong answer, Mr. Smartass.

But thats how real world math goes.  You have to understand the question before you can hope to answer it. No point figuring out the right answer to the wrong question.