If abcd and a,b,c and d are integers, what is the probability that

Question

If  a>b>c>d  and a,b,c and d are integers, what is the probability that product  abcd  is positive?

(1) Only one number is on left side of 0 on the number line.
(2)  bc  is positive

NEW question

niks18 · Answer

to find probability of abcd>0 Statement 1: From this we know that one number is negative but others can be positive or 0 . Hence abcd can be positive or 0 . Insufficient Statement 2: Nothing mentioned about a & d . Insufficient Combining 1 & 2: we know only 1 number is negative and as bc>0 so both cannot be negative or 0 . hence a>b>c>0 and d<0 . Therefore abcd<0 . Sufficient Option C

Octobre · Answer

Hello chetan2u

Does not statement 1 imply that product abcd can be zero (if c equals zero) or negative (if all 3 c, b and a are positive) but never positive? Which would mean that probability of it being positive is zero? And that would make statement 1 alone sufficient?

Thanks for explaining what I might be missing.

u1983 · Answer

Hello Mods (  chetan2u  ,  gmatbusters  ,  amanvermagmat  ,  Bunuel  ,  VeritasKarishma  )....... could we please check the OA again ?

GMATBusters · Answer

yes , 
there seems a typo in OA.

u1983 · Answer

What if .... if one of the integers is 0 ? 0 is interger , but neither +ve nor -ve.....

now, what the next blunder I am up to

cngthanh190 · Answer

I think C is correct:
A. 1 number is negative, --> a: negative
Case 1: a=-2, b=0, c=1, d=2--> abcd<0
Case 2: a=-2, b=1, c=2, d=3--> abcd>0
Insufficient. 
B. insufficient.
a + b: eliminate case 1 --> sufficient.

nitesh50 · Answer

Hi  gmatbusters 
Is saying  what is the probablilty  of abcd>0 the same as  Is abcd>0?

If yes what is the difference? and how would we calculate the exact probability?

If not?
Then the question is asking Q.abcd>0?

Statement 1:
Only one term is negative.
has to be D=-ve
A,B,C can be positive or 0
Case 1: Ab positive c=0 d=-ive . Ans 0 
SO abcd is not positive.

Case 2: Abc are positive 
so abcd will be negative.
so abcd is not positive.

IN both cases the answer is NO.
Hence I marked this statement as suuficient.

Can you tell me where I am going wrong?

chetan2u · Answer

Sorry, there was a typo ... edited it.
Thanks

chetan2u · Answer

Hi..

for answering a probability question we should be aware of the properties of the number in question.
here we have variables and we should know about them. here it literally becomes a question Is abcd positive..
Statement II will not give an answer,,..
since bc is positive, a is surely positive so abc is positive but we still do not know about d, so insuff.
if d is positive probability is 1, if not probability is 0

apurvgodbole · Answer

Statement 1
Only one number is negative. Implies the remaining three are greater than zero or two of them are greater than zero and one of them is zero.
In either case the probability of abcd being positive is zero. 
Sufficient

Statement 2
bc is positive. Implies either both 'b' and 'c' are positive or both are negative. 
If 'b' and 'c' both are positive, then 'a' must also be positive. So 'd' can be zero or negative. Probability of abcd being positive in both cases is zero.
If 'b' and 'c' are both negative, then 'd' must be negative. But, 'a' can be negative or zero or positive. Hence probability here can't be determined.
Therefore, Insufficient

Answer - A

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u1983 · Answer

Np. But still I would have got the ans wrong................ again I mixed up DS yes/no VS value Q ....... Thanks a bunch chetan2u .....completely fine ......... Thanks again

Salsanousi · Answer

Quite interesting!

We know one number is on the left side of zero so it means we have 1 negative.

- * 3 other options (whether they’re all or all 0)

We get an answer of NO. Because 0 is neither positive nor negative. So it is not positive.

If - * + then we have an answer of NO it is negative not positive.

For statement 2)

BC is positive is not necessarily indicative of anything. It only means they are the same sign either both positive or both negative

b = 3 and c = 2

D could -ve or +ve so we have two different answers

Posted from my mobile device

bumpbot · Answer

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If a>b>c>d and a,b,c and d are integers, what is the probability that

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