I don't think the question was looking for a precise answer, but rather an approximate one. As he said, most programmers don't even get in the ballpark, and you

I don't think the question was looking for a precise answer, but rather an approximate one. As he said, most programmers don't even get in the ballpark, and you'll note his question didn't mention cache or cache size. In fact, the way the question is phrased, you could answer for a system that had no cache whatsoever if you wanted to, though I'd go with some common cache architecture.