Veritas Prep 10 Year Anniversary Promo Question #5

Question

Veri tas Prep 10 Year Anniversary Promo Question #5 One quant and one verbal question will be posted each day starting on Monday Sept 17th at 10 AM PST/1 PM EST and the first person to correctly answer the question and show how they arrived at the answer will win a free Veritas Prep GMAT course ($1,650 value). Winners will be selected and notified by a GMAT Club moderator. For more questions and details please check here: veritas-prep-10-year-anniversary-giveaway-138806.html To participate, please make sure you provide the correct answer (A,B,C,D,E) and explanation that clearly shows how you arrived at it. Winners will be announced the following day at 10 AM Pacific/1 PM Eastern Time. What is the value of integer q ? (1) qr + qs = r + s (2) r eq{-s}

Bunuel · Answer

Winner:    Vips0000

Official Explanation:   Answer is C

Statement 1 at first appears to be sufficient, as one can factor out the common  q  to get:  q(r + s) = r + s . This would suggest that  q  equals one. But you must ask about statement 2, “why are you here?”. Statement 2 is clearly not sufficient, but it sheds a bit of light on something you may not have considered with statement 1. If  r  were to equal  -{s} , then  r + s  would be 0. And in that case, our revised equation for statement 1,  q(r + s) = r + s , is true for any value of  q . So statement 2 is critical - it shows us that statement 1 is not sufficient alone, but that along with statement 2 we can rest assured that  q  is 1. The correct answer is C.

Vips0000 · Answer

Ans is C

A gives us either q=1 or r=-s.. but can not say 
B gives us r not equal to -s..

Combining we get q=1
So C

fameatop · Answer

Answer is C
1) insufficient as q can be 1 or 0
2) Insufficient 
3) Q = is 1 as r is not equal to - s

adineo · Answer

ans is c

because we need b otherwise we cant cancel 0 on both sides

adineo · Answer

@ mods..i just could not see the question before 10:03..i tried refreshing but it was linking to question number 3 !

gamelord · Answer

(1) qr + qs = r + s <=> q (r+s) = (r+s) <=> r + s = 0 or q = 1
Can't determine q -> not sufficient
(2) r is different to -s => r+s <> 0 . No information about q -> not sufficient

(1) + (2): r+s <> 0 & q(r+s) = (r+s) => q =1
Sufficient

My answer is C

huyentran · Answer

The answer is: ( C)
Solution:
What is the value of integer ?

We have: (1) qr+qs = r+s
Then q(r+s) = r+s => (q-1)(r+s)=0 => q=1 or r=-s. So it’s not Sufficient
Together with (2) r≠-s, we have q=1.So the answer is C

novam · Answer

Ans is C.
stmt 1) qr + qs = r + s => q(r+s) = (r+s) 
=> q=1 if (r+s) not equal to 0 OR q does not have unique value if (r+s)=0
stmt 2) r not equal to -s => (r+s) not equal to 0
Hence, to find unique value of q stmt 1) & 2) both necessary

nnitingarg · Answer

I will choose Answer C:

Statement 1:
qr + qs = r + s
q(r + s) = r + s

most of the people prefer to divide both sides by (r + S) and hence conclude that q = 1. As per my understanding, GMAT does not prefer that way because it eliminates one solution. (if one does as this, one will miss (r + s) = 0 as answer)

As per my understanding, 
q(r + s) = r + s
q(r + s) - (r + s) = 0
(r + s)(q - 1) = 0

either (r + s) = 0 or (q - 1) = 0. if (r + s) = 0 then q can have any value.
statement 1 insufficient.

Statement 2:
r is not equal to -s does not provide any information about value of q
statement 2 is insufficient.

statement 1 and 2:
from statement 1, we know that either (r + s) = 0 or (q - 1) = 0
but from statement 2, we know that r NE -s, so (r + s) NE 0

substitute this in statemet 1. we will get (q - 1) = 0

q = 1

sufficient

OA please?

vivekvasireddy · Answer

Ans : C
R+c should not be 0 in the 1st equation to get a value for Q
This is confirmed by 2nd statement. " R+c not= 0"
We need both statements together so ans is C

pinokio · Answer

C.
- (2) is not sufficient since irrelevant. BD out
- (1) q (r+s) = r + s
(q-1)(r+s)= 0
=> Either (q-1) = 0 or (r+s) = 0. Not sufficient in case of (r+s) = 0. A out
- Both (1)&(2), from (2) we have r+s <>0, combine with (1) we have q = 1: sufficient

voodoochild · Answer

C
a - if r+s = 0; q could be anything
B - not sufficient
C- works. Q=1

thevenus · Answer

why not (A)?
(i)q(r+s)=(r+s)
q=? ...(doesn't matter what r or s is , we have to find the q ;not to check whether is positive negative or zero);the value cant be found out insufficient so (A) is 
sufficient
(ii) lacks info-insufficient

prep · Answer

1) qr + qs = r + s thus, q (r+s) = (r+s). Now you can't divide since r+s=0. If r+s is not 0, then q=1. Hence insufficient
2) r+s is not = 0. no information about q.

Both combined - we can say that q = 1.
Thus, answer is C

mbaiseasy · Answer

A will only be the answer if statement (1) is sufficient to provide one exact answer to the question, what is the value of q?

yashii9 · Answer

A.

q(R+S) =(R+S)

Let the value of r and s be anything q will always be equal to 1.

Vips0000 · Answer

Not correct approach. 
what if R=S=0 then? 
Q(R+S) = 1*(R+S) => Q=1 ?
as well as Q(R+S)=10*(R+S) =>Q=10 ?
and it can be shown to be true for any other number... So first you can not claim Q=1 this way.
Second, the conclusion u reached
Q(R+S) =(R+S) => Q=1 
this is arrived when you've divided both sides by (R+S). Which can not be done if R+S = 0, as it will be illegal operation to divide by 0. Unless you are certain about r+s <>0, you can not reach to conclusion.

yashii9 · Answer

Dear vips - if r or s is 0... the equation will be 0 on both side..and u can not get the value of q.

if either r or s is 0 u still get q=1 
isnt it?

Also if we are to consider this as an unanswerable case - then even point 2 wont help. r not equal to -s...could well mean r =s =0 again no answer and then reach the conclusion to be E.

What do you say?

sdpp143 · Answer

Ans:C
 Statement1 :given qr+qs=r+s
=>q(r+s)=r+s
=>q=1 only when r not equal to -s
If r=-s,then q is undefined
Hence Statement1 is insufficient
 Statement2: given r not equal to -s
No information about q
Hence Statement2 is insufficient

By combining both  statements 1 and 2 
q=1 when r not equal to -s
Hence C is the correct answer

Veritas Prep 10 Year Anniversary Promo Question #5

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards