- Tue Dec 13, 2016 1:04 pm
This one is all about numbers and percentages, Chica, and the authors love to mess with you using those.
Try this analogy for a second:
50% of the students in this school are female, and 50% of the students identify themselves as female. Therefore, 100% of the students in this school are either female or identify themselves as such.
The obvious flaw here is that could be (and in this case, there probably is) a substantial overlap between those that are female and those that identify themselves as female. You can't add the two percentages together, because you have no way of knowing that they are completely separate groups.
Answer E points out the possibility of an overlap between the two groups (those with drainage issues and those with structural problems), meaning the total could be lower than the 60% claimed. It could, in fact, be a complete overlap, and only 30% have those problems!
When presented with number or percentage ideas, ask yourself what other numbers you know or need to know in order to analyze the argument. Consider whether the groups being compared might overlap, or whether they might not overlap. If you have to imagine some numbers to help you visualize the problem, keep them small and simple. I like to use 100 as the total for whatever is being analyzed, so if I had to I would imagine that there were only 100 houses in this town.
Have fun with those numbers!
Adam M. Tyson
PowerScore LSAT, GRE, ACT and SAT Instructor
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