#5 - Resident: Data indicates that 30 percent of the houses

[Administrator]

Please post below with any questions!

[ChicaRosa]

I had a hard time with this question and I don't know why E is correct?

Based on reading the stimulus it added both percentages (30% inadequate drainage and 30% structural defects) to conclude that 60% of the houses had some kind of problem that threatened their integrity.

To be honest I thought it was A but later realized it was wrong because the stimulus isn't using proportions to represent a numerical conclusion about the houses.

Thank you!

[Adam Tyson]

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!

[kyunglt]

I knew that the flaw was 30% + 30% = 60% of all of the houses. However, if Flaw questions are in the "Prove" family, which means that we are to take the facts of the stimulus as true, how then do we get to doubt the explicit numbers asserted in the stimulus?

[Adam Tyson]

Being in the Prove family, kyunglt, means that we must accept the premises as stated and that our answers must be based on an analysis of what we read, with no outside information. It does NOT mean that we have to accept the conclusion! The premises here can be accepted as completely true - 30% have problem X and 30% have problem Y - while the conclusion does not have to follow from them because of the possibility that the two groups overlap. We aren't doubting the premises - the facts - but instead we are showing that those premises do not necessarily support the author's conclusion, and describing why that is so. That's the case with pretty much every Flaw question - the premises are typically accepted, but the conclusion doesn't have to follow from them, and we need to say why that conclusion need not follow.

[jordankarpoff]

can you explain why d is wrong

[Ryan Twomey]

Hey Jordan Karpoff,

So the stimulus said 30 percent of the houses have site drainage issues. The stimulus also said 30 percent of the houses have structural defects. Then the stimulus concluded 60 percent of the houses have some type of issue.

The flaw is: that the argument did not consider that there could be some overlap between these two problems. If even one house has both of these problems then their conclusion is flawed. Which is what answer choice E points out.

Answer choice D is wrong because at least 40 percent of the houses have neither problem. So answer choice D is irrelevant in pointing out that many houses might not have either problem. That is true. There are many houses that have neither problem. That is not what makes the stimulus flawed.

However, this is a question where you need to see the flaw in the stimulus before going to the answer choices. This is a question where it is more important to understand why the correct answer is correct instead of why your answer is wrong because the correct answer in this case should be derived from a pretty strong prephrase. I would recommend going to the numbers and percentages lesson logical reasoning in lesson 9 in the powerscore lesson book or the numbers and percentages lesson in the bible.

I hope this helps.

Best,
Ryan