Absolute Value - Help Please

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Absolute Value - Help Please

by siddarth » Tue Sep 23, 2008 4:27 am
Is |x-z|>|x-y|

1) |z|>|y|
2) 0>x

My solution was as follows:

the original equation will give us 2 results:

a) x-z>x-y => x-z-x+y>0 => y+z>0.
b) -x+z>-x+y => -x+z+x-y>0 => z-y>0.

Now Statement 1 will satisfy both these conditions, so my answer is Statement 1 is enough to answer the question.

Statement 2 by itself is of no help.

The Answer however is E.

Could someone please help me out with this. I always get confused with Absolute Value questions.

Should i instead take numbers and work out such problems.

Thanks
Source: — Data Sufficiency |

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by gdrea3 » Tue Sep 23, 2008 4:57 am
Start with the easier statement, (2)--> 0>x INSUFFICIENT
Statement 1 states that the absolute value of z is greater than the absolute value of y, but it doesn't tell us about the value of x-->INSUFFICIENT.

Put the two statements together:
so if 0>x, pick a negative number for x
and if the abolute val of z>absolute val of x, pick positive AND negative #s (remember that # is the absolute value brackets are POSITIVE AFTER YOU DO ANY ADDITION, SUBTRACTION, MULTIPLICATION, etc:

Use -1 for x, -3 for z, and -2 for y:
|x-z|>|x-y| -->|-1+3|>|-1+2| so is 2>1? YES

Use -10 for x,-4 for z, and -2 for y:
|x-z|>|x-y| -->|-10+4|>|-10+2| so is 6>8 NO

BOTH statements together are insufficient

Junior | Next Rank: 30 Posts
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by siddarth » Tue Sep 23, 2008 5:15 am
Thanks, got it
gdrea3 wrote:Start with the easier statement, (2)--> 0>x INSUFFICIENT
Statement 1 states that the absolute value of z is greater than the absolute value of y, but it doesn't tell us about the value of x-->INSUFFICIENT.

Put the two statements together:
so if 0>x, pick a negative number for x
and if the abolute val of z>absolute val of x, pick positive AND negative #s (remember that # is the absolute value brackets are POSITIVE AFTER YOU DO ANY ADDITION, SUBTRACTION, MULTIPLICATION, etc:

Use -1 for x, -3 for z, and -2 for y:
|x-z|>|x-y| -->|-1+3|>|-1+2| so is 2>1? YES

Use -10 for x,-4 for z, and -2 for y:
|x-z|>|x-y| -->|-10+4|>|-10+2| so is 6>8 NO

BOTH statements together are insufficient