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How many families who live in the town own neither a car nor

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guest
 Post subject: How many families who live in the town own neither a car nor
 Post Posted: Mon Nov 17, 2008 10:46 pm 
Three thousand families live in a certain town. How many families who live in the town own neither a car nor a television set? (1) Of the families who live in the town, 2,980 own a car. (2) Of the families who live in the town, 2,970 own both a car and a television set.


I totally no idea ? who can help me this question ?
i know ABI= a+b+i -ab but i still can not figure out?
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kylo
 Post subject:
 Post Posted: Tue Nov 18, 2008 7:25 am 
it's a clear E.



Thanks!
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guest
 Post subject: do anybody know? how to solve this question?
 Post Posted: Tue Nov 18, 2008 3:08 pm 
many thanks
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hoho
 Post subject: can anybody explain this questions?
 Post Posted: Thu Nov 20, 2008 6:25 pm 
i did not understand !
thanks
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RonPurewal
 Post subject: Re: How many families who live in the town own neither a car
 Post Posted: Sat Nov 29, 2008 8:41 am 
Offline
ManhattanGMAT Staff


Posts: 7146
guest wrote:
I totally no idea ? who can help me this question ?
i know ABI= a+b+i -ab but i still can not figure out?


if you know that formula, just plug into it.
for onlookers:
"ABI" is, basically, "everyone total".
"a" is "has tv"
"b" is "has car"
"i" is "has neither"
"ab" is "has both"

by the way, this is a prime illustration of why using the double-set matrix is better than using formulas. we have a user who knows the formula cold but is STILL confused by it; that will not happen with the double set matrix.

you're looking for "i" (in your terms).

using your formula,
3000 = 2980 + 2970 + i - "ab"

the problem is, you don't know "ab" (the number who have both). this number could range anywhere from 2950 to 2970, but it's sufficient just to realize that it can have more than one value.
since i depends on ab, INSUFFICIENT.

--

this problem is easier to visualize with the double set matrix.
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Guest
 Post subject:
 Post Posted: Tue Dec 30, 2008 7:26 am 
I'm confused here u said ab= both, statement 2 says 2,980 own both
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Guest
 Post subject:
 Post Posted: Tue Dec 30, 2008 7:27 am 
Anonymous wrote:
I'm confused here u said ab= both, statement 2 says 2,980 own both


Sorry 2,970...
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JonathanSchneider
 Post subject:
 Post Posted: Mon Jan 05, 2009 2:06 pm 
Offline
ManhattanGMAT Staff


Posts: 380
Yeah, I think we may have overlooked that above. You are right: we do know the total for those who owned both (2970). Nonetheless, we do NOT know the total for those who owned only a TV.

I second Ron that a double-set matrix is prefered here. Discussed in our Word Translations guide book.
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