Data Sufficiency

Is xy > 0 ?

1. x/y < 0
2. x + y < 0

I'm going to say E..

1. tells us that either x or y must be negative but both numbers cant be positive or negative - sufficient
2. tells us that when the numbers are added together they're still negative, so the negative number must be larger - sufficient

may not be right.. but i tried

A

1. x or y must be negative but not both. Thus XY will always be less than 0......sufficient.
2. x + Y < 0.....-4 + -6 = -10 or -10 + 2 = -8......not sufficient.

harsh.champ wrote:Is xy > 0 ?

1. x/y < 0
2. x + y < 0

In my opinion the right answer is A.

(1) x/y < 0 implies that x and y have opposite sign. So xy<0. SUFF.
(2) x+y < 0 does not tell us if x and y have opposite sign or they are both negative. INSUFF.

harsh.champ wrote:Is xy > 0 ?

1. x/y < 0
2. x + y < 0

xy> 0 ----> either x and y both >0 or x and y both <0
St.1 : x/y <0 so x>0 and y<0 or x<0 and y>0 ------------------insufficient
St.2: x+y <0 so x<-y --> if y is +ve x/y <-1 ie. x is -ve
and if y i -ve x/y <1 i.e x might be +ve or -ve..
so insufficient
combined:
since st. 1 and the ques xy>0 are giving exactly opposite conditions
so st.1 and st.2 combined will give result which are not favorable so insufficient.........

Ans E

shashank.ism wrote:

harsh.champ wrote:Is xy > 0 ?

1. x/y < 0
2. x + y < 0

xy> 0 ----> either x and y both >0 or x and y both <0
St.1 : x/y <0 so x>0 and y<0 or x<0 and y>0 ------------------insufficient
St.2: x+y <0 so x<-y --> if y is +ve x/y <-1 ie. x is -ve
and if y i -ve x/y <1 i.e x might be +ve or -ve..
so insufficient
combined:
since st. 1 and the ques xy>0 are giving exactly opposite conditions
so st.1 and st.2 combined will give result which are not favorable so insufficient.........

Ans E

I don't know why you concluded St1 is insufficient, even when u solved correctly though.
When u know from ST 1 that either X or Y has to be less then 0 then result of XY will always be < 0 - Hence, sufficient.

sumanr84 wrote: I don't know why you concluded St1 is insufficient, even when u solved correctly though.
When u know from ST 1 that either X or Y has to be less then 0 then result of XY will always be < 0 - Hence, sufficient.

SUMANR84 I think you are very correct in saying that xy <0 so it clearly says xy is not >0
Hence I should go with Ans AThanks suman..for pointing this mistake..

hi all,

i guess the first one tells us that one of the number is -ve, so if that is the case, then XY has to be less than 0, then we know this case is sufficient to come to conclusion!-- hence sufficient

but in the 2nd case, x+y is less than 0, this can happen in 2 cases, 1st when both these nos. is -ve or when the larger of these 2 nos. is -ve. in this case.. since there are 2 conditions. we need to see for both the condition, do we get the same answer for our question which is XY>0 ... when the larger no. is -ve then, the answer is -ve.... when both the nos. are -ve then the answer is +ve.... hence we have 2 answers this case... n hence insufficient

so i guess only answer 1 is sufficient to answer... n answer 2 is not sufficient.

Victorious!
Rohan....