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GMAT prep - Rate of chemical

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GMAT prep - Rate of chemical

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A rate of a certain chemical reaction is directly proportional to the square of tge concentration of chemical A present and inversely proportional to a concentration of chemical B present. If the concentration of chemical B is increased by 100%, which of the following is clost to the percent change in the concentration of chemical A required to keep the reaction rate unchanged?

1. 100% decrease
2. 50% decrease
3. 40% decrease
4. 40% increase
5. 50% increase

I have no idea what it is about. Thanks for explanation.

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Junior | Next Rank: 30 Posts Default Avatar
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I'm so sorry, I should have posted it in problem solving section.

Sorry for my mistake.

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Master | Next Rank: 500 Posts
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Option D.

sqauare root of 2 (approx)= 1.4

Regards,

_________________
Cubicle Bound Misfit

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Newbie | Next Rank: 10 Posts Default Avatar
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Posted:
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Test Date:
Aug 2008
Target GMAT Score:
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Lets say rate = K * (a^2 / b) - Eq1
Now b is increased by 100%

therefore new
rate = K * (a1^2/2b) - Eq2
where new a is = a1

Eq1 = Eq2
(a^2 / b) = (a1^2/2b)

a1 = Sqrt(2) * a = 1.414a

Clearly a is approx 40% increased!
D is the answer!

OA please?

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Junior | Next Rank: 30 Posts Default Avatar
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You're right, answer is D.

Thanks guys for explanation.

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