Common knowledge as an indicator of business fit has been proven to be useless (and should be obvious on examination). Knowing which small town is in which country is simply irrelevant to whether a candidate apply for a management position can improve morale or productivity, or whether a candidate applying for a marketing position has any idea on how to convince customers to purchase a product.
Common knowledge simply has no relation to actual skill in a set field and neither does it have any relation to intelligence. This is doubly so true today with any of these questions being answerable within seconds on a smartphone, and the thoughts instead turned to actually using the information to accomplish something useful.
It's possibly a good indicator of how well they absorb information and/or how much they read or pay attention to the news, or wherever they are learning these random facts from. I'm not saying that means a lot though, and I definitely would have failed this test.
Not necessarily, there are too many variables. The person in question may not own a radio. He may have spent a number of months in hospital because his wife got sick. An older person may have learned one of the facts over twenty years ago, and has since forgotten it. By random chance, one of the facts may have been heard by the candidate 10 minutes beforehand.
In short: it's a good indicator of so many random variables as to be simply an indicator of chaos itself. Don't use anything like this in any kind of test in which the results count - you will invariably get the short end of the stick with one or more candidates. Stick to measures that directly affect the job at hand, and culture fit.
I'm sure the answers to the questions would correlate fairly well to that even if there is some noise. And since there are a lot of questions that would smooth out the ones people get right or wrong just by chance.
Common knowledge simply has no relation to actual skill in a set field and neither does it have any relation to intelligence. This is doubly so true today with any of these questions being answerable within seconds on a smartphone, and the thoughts instead turned to actually using the information to accomplish something useful.