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Can someone please provide detailed explanations. Thanks!

Firstly, for any value of n, K will always be a positive entity.

From F.S 1, we have \(10^{-4} < K < 10^{-3}\) , multiply across by \(10^4 \to\) \(10^{-4+4} < K *10^4< 10^{-3+4}\)\(\to\) \(1< 9.87*10^{n+4} < 10\)\(\to\) Thus, the only value which n can assume is n =-4.Sufficient.

F.S 2 can be re-written as the same as F.S 1, Thus Sufficient.

Re: If n is an integer and k = 9.87 X 10^n, what is the value of [#permalink]

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25 Aug 2013, 10:53

1

This post received KUDOS

Expert's post

SKTRain wrote:

Bunuel wrote:

bluecatie1 wrote:

Hi Bunel, I really do not understand how to solve the second part of data sufficiency. Can you please explain?

Consider this: 10<20<100 can be rewritten as 1/100<1/20<1/10.

The same way: 10^3<1/k<10^4 can be rewritten as 1/10^4<k<1/10^3 --> the same equation as in the first statement.

Hope it's clear.

thank you, but why is there a change in the order of the inequality. I though u only change the algebraic sign if you multiply with a negative number. but here u merely multiply with a fraction.

Simplest way to understand to consider an example: 2<3<4 --> 1/4<1/3<1/2. _________________

Re: If n is an integer and k = 9.87 X 10^n, what is the value of [#permalink]

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22 Aug 2013, 07:21

Great Method... I would have never thought of that to multiply \(10^4\) that step made the problem really easy... would there be any other alternative? _________________

Re: If n is an integer and k = 9.87 X 10^n, what is the value of [#permalink]

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25 Aug 2013, 10:51

Bunuel wrote:

bluecatie1 wrote:

Hi Bunel, I really do not understand how to solve the second part of data sufficiency. Can you please explain?

Consider this: 10<20<100 can be rewritten as 1/100<1/20<1/10.

The same way: 10^3<1/k<10^4 can be rewritten as 1/10^4<k<1/10^3 --> the same equation as in the first statement.

Hope it's clear.

thank you, but why is there a change in the order of the inequality. I though u only change the algebraic sign if you multiply with a negative number. but here u merely multiply with a fraction.

Re: If n is an integer and k = 9.87 X 10^n, what is the value of [#permalink]

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18 Sep 2013, 19:29

Hi Bunuel, Even I was stuck in the second part, can you please explain me with some examples especially if there are negative numbers involved ( since the sign flips )

Re: If n is an integer and k = 9.87 X 10^n, what is the value of [#permalink]

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09 Oct 2014, 09:43

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