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Sub 505 (Easy)|   Algebra|            
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paki
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Does the product jkmn equal 1? Updated on: 07 Oct 2022, 08:18
Originally posted by paki on 16 Dec 2005, 14:49.
Last edited by Bunuel on 07 Oct 2022, 08:18, edited 2 times in total.
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B
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!

Difficulty:

5% (low)

Question Stats:

86% (00:54) correct 14% (01:00) wrong based on 1028 sessions

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Does the product jkmn equal 1?

(1) \(\frac{jk}{mn} = 1\)

(2) \(j = \frac{1}{k}\) and \(m = \frac{1}{n}\)
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B
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Pure algebraic questions like this one are no longer part of the GMAT Data Sufficiency syllabus.
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Does the product jkmn equal 1? 16 Dec 2005, 16:05
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Does the product JKMN = 1?

(1) (JK)/(MN) = 1

(2) J= (1/K) and M = (1/N)
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B.

1) JK/MN = 1 ..... JK = MN , all we know is that JK and MN are equal, but could be any value, not just 1..... INSUFF

2) Substitute: (1/K)*K*(1/N)*N = 1.... SUFF
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Does the product jkmn equal 1? 31 Oct 2013, 18:03
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Bumping this up for a quick question.

Original question is asking whether jkmn = 1.

I rephrased to: does jk = 1/(mn) by dividing both sides by mn

Statement 1: jk/mn = 1 --> rephrase to jk = mn
Since jk = mn and does not equal 1/mn, I said this was sufficient.

Statement 2: j = 1/k; m = 1/n --> rephrase to jk = 1 and mn = 1
Sufficient

I chose answer choice D while the OA is B. Can someone please explain where I went wrong?
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Does the product jkmn equal 1? 01 Nov 2013, 01:10
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NvrEvrGvUp
Bumping this up for a quick question.

Original question is asking whether jkmn = 1.

I rephrased to: does jk = 1/(mn) by dividing both sides by mn

Statement 1: jk/mn = 1 --> rephrase to jk = mn
Since jk = mn and does not equal 1/mn, I said this was sufficient.

Statement 2: j = 1/k; m = 1/n --> rephrase to jk = 1 and mn = 1
Sufficient

I chose answer choice D while the OA is B. Can someone please explain where I went wrong?
Show more

jk = mn and jk = 1/mn does not exclude each other.

Does the product JKMN = 1?

(1) (JK)/(MN) = 1 --> JK=MN. The question becomes: does (MN)^2=1. We don't know that. Not sufficient.

(2) J= (1/K) and M = (1/N) --> JKMN = 1/K*K*1/N*N = 1. Sufficient.

Answer: B.
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Does the product jkmn equal 1? 01 Nov 2021, 22:23
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Bumping this up for a quick question.

Original question is asking whether jkmn = 1.

I rephrased to: does jk = 1/(mn) by dividing both sides by mn

Statement 1: jk/mn = 1 --> rephrase to jk = mn
Since jk = mn and does not equal 1/mn, I said this was sufficient.

Statement 2: j = 1/k; m = 1/n --> rephrase to jk = 1 and mn = 1
Sufficient

I chose answer choice D while the OA is B. Can someone please explain where I went wrong?

jk = mn and jk = 1/mn does not exclude each other.

Does the product JKMN = 1?

(1) (JK)/(MN) = 1 --> JK=MN. The question becomes: does (MN)^2=1. We don't know that. Not sufficient.

(2) J= (1/K) and M = (1/N) --> JKMN = 1/K*K*1/N*N = 1. Sufficient.

Answer: B.
Show more

But what happens if K=0 or N=0? It would be wrong to assume 1/K*K=1 because of the indetermination. Can someone clarify?
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Does the product jkmn equal 1? 02 Nov 2021, 01:26
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HermesM11
Bunuel
NvrEvrGvUp
Bumping this up for a quick question.

Original question is asking whether jkmn = 1.

I rephrased to: does jk = 1/(mn) by dividing both sides by mn

Statement 1: jk/mn = 1 --> rephrase to jk = mn
Since jk = mn and does not equal 1/mn, I said this was sufficient.

Statement 2: j = 1/k; m = 1/n --> rephrase to jk = 1 and mn = 1
Sufficient

I chose answer choice D while the OA is B. Can someone please explain where I went wrong?

jk = mn and jk = 1/mn does not exclude each other.

Does the product JKMN = 1?

(1) (JK)/(MN) = 1 --> JK=MN. The question becomes: does (MN)^2=1. We don't know that. Not sufficient.

(2) J= (1/K) and M = (1/N) --> JKMN = 1/K*K*1/N*N = 1. Sufficient.

Answer: B.

But what happens if K=0 or N=0? It would be wrong to assume 1/K*K=1 because of the indetermination. Can someone clarify?
Show more

Division by 0 is not allowed: anything/0 is undefined. So, for (2) neither k nor n can be 0 because in this case 1/k and 1/n would be undefined and could not equal to real numbers j and m.

Does this make sense?
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HermesM11
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Does the product jkmn equal 1? 02 Nov 2021, 13:23
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Bunuel
HermesM11


But what happens if K=0 or N=0? It would be wrong to assume 1/K*K=1 because of the indetermination. Can someone clarify?

Division by 0 is not allowed: anything/0 is undefined. So, for (2) neither k nor n can be 0 because in this case 1/k and 1/n would be undefined and could not equal to real numbers j and m.

Does this make sense?
Show more

Got it! But it seems that I need to assume every number on GMAT is real, right? The question doesn’t mention it.

Posted from my mobile device
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Does the product jkmn equal 1? 02 Nov 2021, 13:32
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Bunuel
HermesM11


But what happens if K=0 or N=0? It would be wrong to assume 1/K*K=1 because of the indetermination. Can someone clarify?

Division by 0 is not allowed: anything/0 is undefined. So, for (2) neither k nor n can be 0 because in this case 1/k and 1/n would be undefined and could not equal to real numbers j and m.

Does this make sense?

Got it! But it seems that I need to assume every number on GMAT is real, right? The question doesn’t mention it.

Posted from my mobile device
Show more

Yes, all numbers used are real numbers by default.
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Does the product jkmn equal 1? 05 Aug 2025, 10:17
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