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Does z = 3 ?

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Does z = 3 ?  [#permalink]

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New post 28 May 2017, 00:52
1
00:00
A
B
C
D
E

Difficulty:

  25% (medium)

Question Stats:

74% (01:05) correct 26% (00:53) wrong based on 90 sessions

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Re: Does z = 3 ?  [#permalink]

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New post Updated on: 28 May 2017, 09:11
1
(a) gives the solution of z as -1 and 3 hence insufficient

(b) gives the solution of z as 0 and 3 hence insufficient

On combining both we can answer the question
hence the answer is C

i did it wrong first time :)


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Originally posted by Luckisnoexcuse on 28 May 2017, 01:41.
Last edited by Luckisnoexcuse on 28 May 2017, 09:11, edited 1 time in total.
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Re: Does z = 3 ?  [#permalink]

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New post 28 May 2017, 08:38
mynamegoeson wrote:
(a) gives the solution of z as -1 and 3 hence sufficient

(b) gives the solution of z as 0 and 3 hence sufficient

hence the answer is D


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Why isn't the answer C?
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Re: Does z = 3 ?  [#permalink]

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New post 28 May 2017, 08:42
mynamegoeson wrote:
(a) gives the solution of z as -1 and 3 hence sufficient

(b) gives the solution of z as 0 and 3 hence sufficient

hence the answer is D


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This is an YES/NO data sufficiency question. A statement is sufficient if you can get a definite YES or definite NO answer to the question asked.

Do you have a definite YES or No answer to the question from any of the statements?
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Re: Does z = 3 ?  [#permalink]

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New post 28 May 2017, 08:52
Bunuel wrote:
mynamegoeson wrote:
(a) gives the solution of z as -1 and 3 hence sufficient

(b) gives the solution of z as 0 and 3 hence sufficient

hence the answer is D


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This is an YES/NO data sufficiency question. A statement is sufficient if you can get a definite YES or definite NO answer to the question asked.

Do you have a definite YES or No answer to the question from any of the statements?


In both statements the equation has 2 solutions, and one of them is 3, so it could be a YES or a NOT, am I wrong?
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Re: Does z = 3 ?  [#permalink]

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New post 28 May 2017, 08:56
1
MvArrow wrote:
Bunuel wrote:
mynamegoeson wrote:
(a) gives the solution of z as -1 and 3 hence sufficient

(b) gives the solution of z as 0 and 3 hence sufficient

hence the answer is D


Sent from my iPhone using GMAT Club Forum


This is an YES/NO data sufficiency question. A statement is sufficient if you can get a definite YES or definite NO answer to the question asked.

Do you have a definite YES or No answer to the question from any of the statements?


In both statements the equation has 2 solutions, and one of them is 3, so it could be a YES or a NOT, am I wrong?


Absolutely. That is why the answer is C and not D. When combined we know that z can only be 3, so we have an YES answer to the question.
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Re: Does z = 3 ?  [#permalink]

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New post 28 May 2017, 08:56
There is not a definite yes or definite no in individual cases, but together we get z=3 ,which is sufficient to answer
So answer would be C

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Re: Does z = 3 ?  [#permalink]

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New post 28 May 2017, 09:01
Glad the my reasoning was correct :)
Thanks Bunuel! You guys from Gmatclub are giving me an incredible help in my preparation, and my GMAT is scheduled in two weeks :D
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Re: Does z = 3 ?  [#permalink]

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New post 28 May 2017, 09:09
Bunuel wrote:
mynamegoeson wrote:
(a) gives the solution of z as -1 and 3 hence sufficient

(b) gives the solution of z as 0 and 3 hence sufficient

hence the answer is D


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This is an YES/NO data sufficiency question. A statement is sufficient if you can get a definite YES or definite NO answer to the question asked.

Do you have a definite YES or No answer to the question from any of the statements?


ohh yes need a brainwash...since we have two answers from first equation and two answers from second equation...individually none of them suffice to answer the question, however when we combine them then we can say that z=3 ..hence option C



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Re: Does z = 3 ?  [#permalink]

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New post 28 May 2017, 18:16
Hi,

S1- z^2-2z-3=0 leads to (Z-3)(z+1) or z=3 or z=-1. Not sufficient as we have two solutions here
S2- z^2-3z=0 leads to z(z-3) or z=0 or z=3. Again not sufficient as we have again two solutions here

When we combine these, we get z=3, hence sufficient. C
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Re: Does z = 3 ?  [#permalink]

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New post 29 May 2017, 01:30
Bunuel wrote:

Absolutely. That is why the answer is C and not D. When combined we know that z can only be 3, so we have an YES answer to the question.


Bunuel, I think you should edit this comment as the OA has been revealed before the planned date :)
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Re: Does z = 3 ?  [#permalink]

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New post 29 May 2017, 01:32
utkarshthapak wrote:
Bunuel wrote:

Absolutely. That is why the answer is C and not D. When combined we know that z can only be 3, so we have an YES answer to the question.


Bunuel, I think you should edit this comment as the OA has been revealed before the planned date :)


Yes, it does not make sense to hide the OA now. It's revealed now.
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Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


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Re: Does z = 3 ?  [#permalink]

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New post 16 Sep 2018, 05:20
Luckisnoexcuse wrote:
(a) gives the solution of z as -1 and 3 hence insufficient

(b) gives the solution of z as 0 and 3 hence insufficient

On combining both we can answer the question
hence the answer is C

i did it wrong first time :)


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How did you calculate this? Did you factor the two equations?
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Re: Does z = 3 ?  [#permalink]

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New post 16 Sep 2018, 05:25
Bunuel wrote:
Does z = 3 ?

(1) z is a solution of z^2 − 2z − 3 = 0.
(2) z is a solution of z^2 − 3z = 0



1 leads to z = -1 , 3 so not sufficient

2 leads to z = 0, 3 so not sufficient

Combining, 3 is common

So z is 3

C it is.
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Re: Does z = 3 ?  [#permalink]

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New post 17 Sep 2018, 03:30
Z=3?

St 1: z^2-2z-3=0
Solving it, we get z as 3 or -1 AD/BCE

St 2: z^2-3z=0
Solving it, we get z = 0 or 3 AD/BCE

Combining them, we get z=3.Hence C
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Re: Does z = 3 ? &nbs [#permalink] 17 Sep 2018, 03:30
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