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# Quantitative comparision

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Quantitative comparision [#permalink]  25 Oct 2017, 01:39
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Question Stats:

100% (00:22) correct 0% (00:00) wrong based on 3 sessions
Can anyone tell me
$$a\neq b$$
 Quantity A Quantity B $$\frac{(a-b)}{(b-a)}$$ 1

Manhattan 5lb answer => (a-b)/-(a-b) = -1 so B is correct (Understood)

but why can't we do this like

1) $$\frac{a-b}{b-a}$$ [?] 1
2)(a-b) [?] (b-a) multiplying b-a on both sides
3)(a-b) [?] -(a-b) dividing by (a-b)
4)1 > -1
A is greater according to this method can I know why I cant do this like
[Reveal] Spoiler: OA

Last edited by nikkikoneru on 25 Oct 2017, 02:23, edited 4 times in total.
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Re: Quantitative comparision [#permalink]  25 Oct 2017, 02:06
Expert's post

edit the question in the proper manner.

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Re: Quantitative comparision [#permalink]  25 Oct 2017, 02:25
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Carcass wrote:

edit the question in the proper manner.

Done can you please explain it now sir

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Re: Quantitative comparision [#permalink]  25 Oct 2017, 04:13
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Expert's post
We can't do this because multiplication with a negative number flips the sign of an inequlality

Say $$5 < 7$$ multiply -1 both sides we get

$$-5 > =7$$. Similarly when you multiply (b-a) to both sides it flips the in eqaulity making Quanity A greater which is incorrect!

Never nultiply varianles whose sign you don't know to both sides of an inequality!
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Re: Quantitative comparision [#permalink]  25 Oct 2017, 05:17
sandy wrote:
We can't do this because multiplication with a negative number flips the sign of an inequlality

Say $$5 < 7$$ multiply -1 both sides we get

$$-5 > =7$$. Similarly when you multiply (b-a) to both sides it flips the in eqaulity making Quanity A greater which is incorrect!

Never nultiply varianles whose sign you don't know to both sides of an inequality!

Thank you.
Re: Quantitative comparision   [#permalink] 25 Oct 2017, 05:17
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