Absolutes in DS

This topic has expert replies
Master | Next Rank: 500 Posts
Posts: 107
Joined: Tue Sep 15, 2009 7:18 pm
Location: Pune, India
Thanked: 6 times
GMAT Score:630

Absolutes in DS

by vivekjaiswal » Wed Nov 11, 2009 2:29 am
Example:
Is |x-z|>|x-y|?
1. |z|>|y|
2. 0>x

I always find myself struggling with absolute value problems and I am so frustrated that such questions just leave me blank!!
I don't even know how to approach such questions, substitution is one way I know...but somehow I don't feel confident about numbers that I use for substitution and in the end I spend way too much time on such questions.

Does anyone out there know or has a preset steps to approach such questions.
Or if you could point me to a book/reference where I can build some fundamentals regarding absolute value problems.

Any help will be deeply appreciated.
BTW the OA for the above question is E

Cheers,
Vivek
Source: — GMAT Strategy |

Master | Next Rank: 500 Posts
Posts: 399
Joined: Wed Apr 15, 2009 3:48 am
Location: india
Thanked: 39 times

Re: Absolutes in DS

by xcusemeplz2009 » Wed Nov 11, 2009 2:46 am
vivekjaiswal wrote:Example:
Is |x-z|>|x-y|?
1. |z|>|y|
2. 0>x

I always find myself struggling with absolute value problems and I am so frustrated that such questions just leave me blank!!
I don't even know how to approach such questions, substitution is one way I know...but somehow I don't feel confident about numbers that I use for substitution and in the end I spend way too much time on such questions.

Does anyone out there know or has a preset steps to approach such questions.
Or if you could point me to a book/reference where I can build some fundamentals regarding absolute value problems.

Any help will be deeply appreciated.
BTW the OA for the above question is E

Cheers,
Vivek
HELLO VIVEK
usually its advicable to pick some no. and check the inequality is the best and efficient way to solve...
while going by that way one has to ensure to check all possible ranges

like in this one ...nothing is mentioned about a no..it can be a +ve , -ve , 0 or any fraction...
select some easy numbers from each catogery put and check LHS and RHS first for the given statement such that it holds true for the given condition and then , again check by inserting in the given question,. If for diff sets the answer for the given condition is true but for the question stem is diff then the given statement is insufficicent.....

initially select an int if one is getting diff ans... then no need to do the same for fractions....

remember we need to do the same for 1 and 2 together, before concluding

HTH
It does not matter how many times you get knocked down , but how many times you get up

Master | Next Rank: 500 Posts
Posts: 107
Joined: Tue Sep 15, 2009 7:18 pm
Location: Pune, India
Thanked: 6 times
GMAT Score:630

by vivekjaiswal » Wed Nov 11, 2009 2:54 am
Thanks xcusemeplz2009,

I understand what you are saying there....but the problem is that I start losing a lot of time in selecting numbers and most of the time I am not sure if I am selecting the right number and then my mind starts calculating the time I am losing on the question rather than solving the problem :(

And then I freak out and mark just something and move on :'(

I have been thinking of making flash cards which will have what numbers to use and in what order and in what condition so that I have a set methodology for dealing with such questions....would you support such an approach?

Thanks a lot once again,
Vivek

Master | Next Rank: 500 Posts
Posts: 399
Joined: Wed Apr 15, 2009 3:48 am
Location: india
Thanked: 39 times

by xcusemeplz2009 » Wed Nov 11, 2009 3:29 am
vivekjaiswal wrote:Thanks xcusemeplz2009,

I understand what you are saying there....but the problem is that I start losing a lot of time in selecting numbers and most of the time I am not sure if I am selecting the right number and then my mind starts calculating the time I am losing on the question rather than solving the problem :(

And then I freak out and mark just something and move on :'(

I have been thinking of making flash cards which will have what numbers to use and in what order and in what condition so that I have a set methodology for dealing with such questions....would you support such an approach?

Thanks a lot once again,
Vivek
i understand u position... actually in Q like this one where we have mod on bth side chosing no are easiest way
and if there is no restriction then its better to select +-1,+-2 for int and +-1/2 , +-1/4 for fraction
if q says that z>x then chose accordingly....

for q particularly involving mod on one side...u can go with conventional method but on exam day it will always consume time...

the best think you can do is take a q from the D/s section of this site and use this method ...on practising a lot u will find it easy...on the final Day
It does not matter how many times you get knocked down , but how many times you get up