Is d negative? (1) e + d = -12 (2) e – d

Question

Is d negative?

(1) e + d = -12

(2) e – d < -12

Show SpoilerAnswer and explanation

(1) e+d = -12
=> d = -12-e, however as we don't know anything about e, it could be 1 (thus d=-13) or -13 (thus d=1) = insufficient

(2) e-d < -12
=> d > 12+e, again e can be anything => insufficient

(1) + (2)
from 1: e=-12-d
from 2: e<-12+d
together: -12-d < -12+d => -d < +d

this is only true if d is positive.

Therefore: Answer is C

However that's not the text books answer explanation, so I thought I'd ask you guys for your opinion and if there are any flaws in the answer that I overlooked.

Bunuel · Accepted Answer

Is d negative? (1) e + d = -12. d can be negative as well as non-negative. For example, consider d=0 and e=-12 and d=-1 and e=-11. Not sufficient. (2) e – d < -12. d can be negative as well as non-negative. For example, consider d=0 and e=-13 and d=-1 and e=-14. Not sufficient. (1)+(2) From (1) we have that e = -12 - d, thus from (2) (-12 - d) - d < -12 --> -2d<0 --> d>0. Sufficient. Answer: C.

GMATinsight · Answer

Question : Is d < 0?

Statement 1 :e + d = -12

@e=2, d=-14 We observe that d may be negative
@e=-14, d=2 We observe that d may be Positive

NOT SUFFICIENT

Statement 2 : e - d < -12

@e=-15, d=1, e-d = -16 i.e. Less than -12 We observe that d may be Positive
@e=-15, d=-2, e-d = -13 i.e. Less than -12 We observe that d may be Negative

NOT SUFFICIENT

Combining the Two statements

e = -12-d
and e - d < -12
i.e. (-12-d)- d < -12
i.e. (-12-2d) < -12
i.e. 2d > 0
i.e. d is positive

SUFFICIENT

Answer: option C

Turkish · Answer

(1) e + d = -12 
(2) e - d < -12

1 and 2 alone are not possible.

Together e - d<e + d since -12 = e + d 
0<2d or 0<d is positive . Ans C

Z10201Z · Answer

(1) is not enough (2) e+120=> d>0 In my opinion, the answer is c I may have simplified the question too much, but this is how I solved it

inandout · Answer

the problem is not hard, and since I have completed all set of quantitative quiz from one of members in the forum, i can solve this problem easily.

LadyJedi · Answer

Is d negative?

(1) e + d = -12

(2) e – d < -12

Show SpoilerAnswer and explanation

(1) e+d = -12
=> d = -12-e, however as we don't know anything about e, it could be 1 (thus d=-13) or -13 (thus d=1) = insufficient

(2) e-d < -12
=> d > 12+e, again e can be anything => insufficient

(1) + (2)
from 1: e=-12-d
from 2: e<-12+d
together: -12-d < -12+d => -d < +d

this is only true if d is positive.

Therefore: Answer is C

However that's not the text books answer explanation, so I thought I'd ask you guys for your opinion and if there are any flaws in the answer that I overlooked.

sashiim20 · Answer

Is d negative? (Its a YES/NO Question.) (1) e + d = -12 e = -12 - d -------- (i) We cannot find value of e or d . Hence I is Not Sufficient. (2) e – d < -12 We cannot find value of e or d . Hence II is Not Sufficient. Combining (1) and (2) Substituting value of e from (i) in (2), we get; -12 -d -d < -12 -2d < 0 2d > 0 d > 0 Therefore d is positive. Combining (1) and (2), we get the Answer to question is d negative is NO. Answer (C)...

Gemelo90 · Answer

Both statements alone are not sufficient. If you plug in statement one in statement you get -2d<0. Therefore d is >0. Answer c is correct.

chetan2u · Answer

1) e+d=-12 If e <-12, d will be >0....and NO If e>-12, d Will be negative...YES Insufficient 2) e-d<-12 d>e+12.. If e=-12, d>0 If e=-15, d can be > or <0.. Insufficient Combined.. From 1) e=-d-12.. So -d-12-d<-12.......-2d<0....2d>0.. Sufficient as and is NO

BrentGMATPrepNow · Answer

Target question :    Is d negative?

Statement 1 : e + d = -12  
Let's TEST some values.
There are several values of e and d that satisfy statement 1. Here are two: 
 Case a : d = -6 and e = -6. Notice that e + d = (-6) + (-6) = -12. In this case, the answer to the target question is  YES, d IS negative 
 Case b : d = 1 and e = -13. Notice that e + d = (-13) + 1 = -12. In this case, the answer to the target question is  NO, d is NOT negative 
Since we cannot answer the  target question  with certainty, statement 1 is NOT SUFFICIENT

Statement 2 : e – d < -12 
There are several values of e and d that satisfy statement 2. Here are two: 
 Case a : d = 13 and e = 0. Notice that e - d = 0 - 13 = -13, and -13 < -12. In this case, the answer to the target question is  NO, d is NOT negative 
 Case b : d = -5 and e = -20. Notice that e - d = -20 - (-5) = -15, and -15 < -12. In this case, the answer to the target question is  YES, d IS negative 
Since we cannot answer the  target question  with certainty, statement 2 is NOT SUFFICIENT

Statements 1 and 2 combined    
Statement 1 tells us that e + d = -12
Statement 2 tells us that e – d < -12
If e + d = -12, then e = -12 - d
Now take e – d < -12 and replace e with -12 - d to get: (-12 - d) – d < -12
Simplify: -12 - 2d < -12
Add 12 to both sides: -2d < 0
Divide both sides by -2 to get:  d > 0     
So, the answer to the target question is  NO, d is NOT negative 
Since we can answer the  target question  with certainty, the combined statements are SUFFICIENT

Answer: C

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push12345 · Answer

Both I and II statements are not giving answers...

Only after combining two
Putting equation 1 in 2 
We get
-2d<0

I.e. d>0 
So C is answer

Give kudos if it helps

Posted from my mobile device

CAMANISHPARMAR · Answer

This is a Yes/No question.

Since number testing is quick, it is advisable to to quickly test some scenarios:-

Attachment:

2018-06-27_23-48-51.jpg [ 184.98 KiB | Viewed 15150 times ]

We have seen above that Statement 1 & 2 are not sufficient by own. We are down to C vs E

Hence we combine the two statements. Scenario 1 satisfies the conditions but Scenario 2 does not satisfy the conditions. We need to analyse this further. We need a concrete proof before we conclude either way.

Since it is given that e + d = -12; therefore e = -12 - d
Statement (2) states that e – d < -12 therefore substitute e = (-12 - d) to get: (-12 - d) – d < -12
Simplification implies that d > 0 or we get a definite "No" to the question "Is d negative?". Hence for both the equations to hold together d have to be positive therefore (C) is sufficient.

gmatzpractice · Answer

(1) e=1; d=-13
e=-13; d=1
Insufficient

(2) e=-13; d=1
e=-14; d=-1
Insufficient

(1) and (2)
-12-d-d < -12
-2d < 0
d>0
Sufficient 
Answer C

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Is d negative? (1) e + d = -12 (2) e – d < -12

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