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# Powerprep PS Grids

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Senior Manager
Joined: 14 Jun 2007
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Powerprep PS Grids [#permalink]  23 Jun 2007, 13:04
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Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions
can anyone explain how to answer this two questions quickly?
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Manager
Joined: 23 Apr 2007
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pp9.jpg....

I think 25 is wrong....just count all the squares above or below the diagonal squares. The ans is 15.

For the second question, i think there is no other way other than trying all the combinations. It would help to uniquely identify every junction uniquely (numbers or alphabets) so as to avoid a retrace!
VP
Joined: 08 Jun 2005
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For the first problem:

(n*n-n)/2 =

(6*6-6)/2 = 15

CIO
Joined: 09 Mar 2003
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For the first one, once you see the patter, you see that there are five boxes in the top row, then 4, then 3, etc. You should learn how to add consecutive numbers quickly:

It's always the middle number times the number of numbers.

So that's 3 (the middle) times 5 (the number of numbers), which is 15.
Senior Manager
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AugiTh wrote:
pp9.jpg....

I think 25 is wrong....just count all the squares above or below the diagonal squares. The ans is 15.

For the second question, i think there is no other way other than trying all the combinations. It would help to uniquely identify every junction uniquely (numbers or alphabets) so as to avoid a retrace!

you said the magic word... combinations... )

is there a way to solve this using nCk or permutations? you will always have to walk up 3 streets and over 2....

i just don't think the GMAT wants us to trace a grid, they are testing us on something here
Director
Joined: 13 Mar 2007
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first one - 6C2 = 15
Manager
Joined: 23 Apr 2007
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Ah nice one grad_mba....this problem (the first one) is analogous to the handshake problem!
Manager
Joined: 23 Apr 2007
Posts: 130
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Kudos [?]: 7 [0], given: 0

for the second one I guess combinations could be a way out
Hmmmm....food for thought!
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