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Must be true?

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Must be true?

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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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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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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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. :)
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