Re:Why does it matter if they come to class? (Score 1)

Must be one of the 10% ....

I'm glad someone noticed my subtle attempt at humor. Believe it or not, percents were the hardest thing to teach. "Percent of", "Increased by a percent", and overlapping percents can confuse people. In the case above, either you can assume I'm trying to hit 100% (which most people are trying to do), or the sample overlaps. The overlapping bit is more of a statistics thing than basic math.