a,b,c

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a,b,c

by shashank.ism » Tue Feb 09, 2010 7:20 am
Let a, b, c be positive reals. (I) and (II) are independent statements.

(I) Minimum value of a^3/4b + b/8c^2 + (1+c)/2a is p
(II) a + b + 2c = 8 and a^2 + b^2 + 2c^2 = 25. Maximum possible value of c is q.

Then which among the following is |p-q|?
5/2
9/4
1/2
3/8
none of these
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by mohit11 » Wed Mar 10, 2010 10:06 pm
I'd say 3/8

Tough question, definitely not solvable in 2 mins !!

I substituted a,b,c as 1, equation one gives ..11/8

from equation 2, C should be 1

P-Q = 11/8 - 1 = 3/8

I know my answer is probably correct, but i don't really have the right reasoning. Very interested to know the trick to solve this question.

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by Stuart@KaplanGMAT » Thu Mar 11, 2010 12:30 am
mohit11 wrote:I'd say 3/8

Tough question, definitely not solvable in 2 mins !!

I substituted a,b,c as 1, equation one gives ..11/8

from equation 2, C should be 1

P-Q = 11/8 - 1 = 3/8

I know my answer is probably correct, but i don't really have the right reasoning. Very interested to know the trick to solve this question.
This is 100% not a real GMAT question; the language used isn't what you'd see on the actual exam. Don't worry about solving it in under 2 minutes.
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by STEVEN SPIELBERG » Sat Mar 13, 2010 11:20 am
What's the OA and source ?
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