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General Age related word question(#5Class recording related)

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rkkarthik
 Post subject: General Age related word question(#5Class recording related)
 Post Posted: Fri Nov 19, 2010 12:00 pm 
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Course Students


Posts: 15
I apologize for the rather rudimentary nature of the question, would appreciate your reply.

I am currently working on Session #5 of 9 (recordings W/ Dan's);
#153 a problem discussed @ 41mins and 38 seconds has a age chart approach. My question is not regarding the answer but the Manhattan method using the age chart.


Now:
J=J
B=J-14

+5
J=J+5
B=J-9 ???

Assume
Now:
J=20
B=20-14 = 6

+5
J=J+5 = 20+5 = 25
B = 25 - 14 = 11
If I substitute B = J - 9 that would make it 25 - 9 = 14
They would still have a 14 year age difference, wouldn't that be the case? How can the age difference reduce over-time??


KK
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danielpatinkin
 Post subject: Re: General Age related word question(#5Class recording related)
 Post Posted: Fri Nov 19, 2010 1:40 pm 
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ManhattanGMAT Staff


Posts: 25
KK,
I'm happy to hear that you are listening to my recordings!

With age problems you have to be very careful moving backwards and forwards in time. Always begin by defining the variables as follows:

J = Jack's Age NOW
B = Bill's Age NOW

J+5 is no longer the same as J. It is a completely different value.
The same with B+5. That is, if B = J-14, then B+5 = J-9. B, itself, does NOT equal J-9.

So, if you assume that J=20, and, therefore, B = 6, then

J+5 = 25 and
B+5 = J-9 = 20-9 = 11

Remember... J is only Jack's age now, NOT Jack's age in 5 years... so J=20... J does not equal 25.

Does that clarify?

Best Wishes,
Dan P
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rkkarthik
 Post subject: Re: General Age related word question(#5Class recording related)
 Post Posted: Sat Nov 20, 2010 10:55 am 
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Course Students


Posts: 15
Wow! Indeed a pleasure to hear from the Master himself ;-) (Dan P); your post did clarify my question.

Thanks for your time

Karthik
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jnelson0612
 Post subject: Re: General Age related word question(#5Class recording related)
 Post Posted: Sat Nov 20, 2010 9:50 pm 
Offline
ManhattanGMAT Staff


Posts: 1857
DanP is indeed the master. :-) Thanks all.

_________________
Jamie Nelson
ManhattanGMAT Instructor
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