Must be true?

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moonlite: Senior | Next Rank: 100 Posts; Posts: 61; Joined: Fri Jun 06, 2008 5:58 am; Thanked: 1 times

by moonlite » Thu Apr 16, 2009 3:26 am

If d>0 and 0<1-c/d<1, which of the following must be true?

1. c>0
ii. c/d<1
iii. c^2 + d^2 >1

a) i only
b) ii only
c) i and ii only
d) ii and iii only
e) i, ii, and iii

OA C I get E, can someone please explain the OA, i'm not sure what i'm missing.

Thanks.

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Source: Beat The GMAT — Problem Solving | Thu Apr 16, 2009 3:26 am

gmat740: MBA Student; Posts: 1194; Joined: Sat Aug 16, 2008 9:42 pmFollowed by: 17 members; Location: Paris, France; Thanked: 71 times; GMAT Score:710

by gmat740 » Thu Apr 16, 2009 3:45 am

how you are getting (e)

you must justify your answers.

1. c>0

for fraction to be less than 1
as d is positive,so if c becomes -ve, so it will add to 1

1 - c/d <1 equation will be violated

ii. c/d<1

For 1- c/d > 0

c/d <1

there can be no other equation

so there arises no question for (III)

Hope this helps

Karan

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mike22629: Master | Next Rank: 500 Posts; Posts: 322; Joined: Fri Mar 27, 2009 3:56 pm; Thanked: 24 times; GMAT Score:710

by mike22629 » Thu Apr 16, 2009 11:41 am

What you are missing is that both c and d can be fractions.

For example:

c= 1/4 and d = 1/2

This still satisfies the requirements and since fractions get smaller as you raise them to exponents, it will be less than one.

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kanha81: Master | Next Rank: 500 Posts; Posts: 431; Joined: Sat Jan 10, 2009 9:32 amFollowed by: 1 member; Thanked: 16 times

Re: Must be true?

by kanha81 » Thu Apr 16, 2009 12:09 pm

moonlite wrote:If d>0 and 0<1-c/d<1, which of the following must be true?

I understand that you had a question and wanted to get a feedback, but next time could you please more explicit in writing out the QUESTION!

For instance, I failed

to understand if 0<1-(c/d)<1 or 0<(1-c)/d<1

Thanks a bunch.

Want to Beat GMAT.
Always do what you're afraid to do. Whoooop GMAT

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