Proportion Data suffiency

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Fokin: Junior | Next Rank: 30 Posts; Posts: 17; Joined: Sun Oct 04, 2009 9:56 pm

by Fokin » Wed Apr 21, 2010 6:39 pm

How to resolve such problem :

John and Paul are standing together on a sunny day. John's shadow is 10 feet long. Paul's shadow is 9 feet long . How tall is Paul?

1)John is 6 feet tall
2) John is tanding 2 feet away from Paul

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Source: Beat The GMAT — Data Sufficiency | Wed Apr 21, 2010 6:39 pm

eaakbari: Master | Next Rank: 500 Posts; Posts: 435; Joined: Mon Mar 15, 2010 6:15 amFollowed by: 1 member; Thanked: 32 times

by eaakbari » Thu Apr 22, 2010 2:20 am

IMO A

The triangles formed by their shadows will be similar.

(1)
Gives us johns height, hence
6/10=x/9
x = pauls height = 5.4 feet

(2) The distance does not matter

Hence A

Please confirm the answer

Whether you think you can or can't, you're right.
- Henry Ford

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Fokin: Junior | Next Rank: 30 Posts; Posts: 17; Joined: Sun Oct 04, 2009 9:56 pm

by Fokin » Thu Apr 22, 2010 4:57 am

eaakbari wrote:IMO A

The triangles formed by their shadows will be similar.

(1)
Gives us johns height, hence
6/10=x/9
x = pauls height = 5.4 feet

(2) The distance does not matter

Hence A

Please confirm the answer

Yes, you are right. Thank you for your help!

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ajith: Legendary Member; Posts: 1275; Joined: Thu Sep 21, 2006 11:13 pmFollowed by: 2 members; Location: Arabian Sea; Thanked: 125 times

by ajith » Thu Apr 22, 2010 6:06 am

Moved to DS forum

Always borrow money from a pessimist, he doesn't expect to be paid back.

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meghash3: Newbie | Next Rank: 10 Posts; Posts: 9; Joined: Wed Mar 24, 2010 4:51 am; Thanked: 1 times

by meghash3 » Thu Apr 22, 2010 12:02 pm

Ans : E ; Both the statements & the ques dont say anything about hte relative pos of John and paul, their shadow lenghts will change according to thier alignment and source of light. We need to know hte angle etc for this, i think its E

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el_torero: Junior | Next Rank: 30 Posts; Posts: 26; Joined: Mon Nov 17, 2008 9:07 pm; Thanked: 3 times

by el_torero » Thu Apr 22, 2010 12:40 pm

It's a strange question, but I think A is the answer.

Here's why:

The setup of the question basically revolves around similar right triangles. Each person's shadow and height form a right triangle with the ray of the sun which shares the same angles.

Therefore, you have J/10 = P/9, where J = John's height and P = Paul's height.

(1) gives you J. Great. Now you can solve for P.

(2) gives you nothing. INSUFF

Hope this helps.

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