But if that's the information you're after, why ask for golf balls and busses? These are real world quantities with decidedly different qualities than whatever appears in standard computing scenarios. Describing how you'd go about troubleshooting a three layer architecture with inordinate network load on the database might be a better question then?
I actually think that's a decent question - in many cases you have to estimate something based on incomplete information in a domain that you aren't an expert in and maybe all you are after is an answer to the nearest order of magnitude.
In my experience some people simply won't answer those questions - not because they can't but because they aren't happy working that way. Of course, in some situations you absolutely do need people who will always work things through from first principles and attempt to give as precise an estimate as they can, but sometimes you don't.
