I know someone will take this the wrong way, but if you're in over your head on an interview question, odds are you won't stand a chance in the actual job.
I don't mean that as any kind of pejorative statement against the OP, we all have our strengths and blind spots, and I'm a firm believer that with a little time and effort, people can be trained how to do almost any job. Problem is, no one wants to invest in training people anymore because employees are seen as a disposable commodity and everything is about meeting short-term fiscal goals. Training budgets are often one of the first things to get the axe, despite the fact that they're the thing that allows a company to maintain any level of long-term sustainability. Who here hasn't worked at a place where only one person knew how some process worked, then they quit or are laid off and everyone's left trying to reverse engineer that person's job.
Given the unfortunate short-sighted nature of the business world today, the OP might well be better served by simply cutting his/her losses and moving on to another company.