[dlu]

More of a logic question, though at its core math is logic and pattern recognition.

I'm certainly going to need a lot more practice if I want to place in Singapore's top 40% of 14/15 year olds

[ricree]

I don't know the context around which this was presented to students, but it's much easier if you think of it as a set operations problem than a pure logic one.

Also nice to see that the age old act of providing irrelevant distracting information in word problems is still alive and well.

A neat problem, though. I'm curious whether I would have gotten it at that age.