Data Sufficiency help

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Data Sufficiency help

by rmanzo » Sat Aug 15, 2009 12:19 pm
Here's the question.

Of the 230 single-family homes built in City X last yr, how many were occupied at the end of the year?

1) Of all the single-family homes in City X, 90 % were occupied at the end of last yr.

2) A total of 7,200 single-family homes in City X were occupied at the end of last yr.

My book is stating E is the correct DS answer, but I say A is the correct answer. Could someone explain the thought process here?

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Re: Data Sufficiency help

by yezz » Sat Aug 15, 2009 1:39 pm
rmanzo wrote:Here's the question.

Of the 230 single-family homes built in City X last yr, how many were occupied at the end of the year?

1) Of all the single-family homes in City X, 90 % were occupied at the end of last yr.

2) A total of 7,200 single-family homes in City X were occupied at the end of last yr.

total build = existing before last year (a)+ 230 built last year(b)

from 1

we dont have the total count of the houses in the city ( ie: a+b)

from 2

obviously insuff

both

90/100(a+b) = 7200 , 2 unknowns with one equation...insuff .. E

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Think of how the word "of" is used

by mark412 » Mon Aug 17, 2009 2:03 pm
I hope this will help:

It is not asking for the total homes/all the homes in City X that were occupied but rather it focuses on the 230 that were built.

1)If the question was what was the total homes occupied in City X at the end of the year, you would be correct in answering A.

2) This jus tells you 7200 homes were occupied, not discussing anything of the 230 that are part of the original stem.

So the answer is E. Always remember how the word "of" is used. It typically points to a smaller amount of something else. Be careful of how it is used in comparison too. "Of" the 230 homes is different than "of" all the homes built.

Hope that helps.