Is a/b

Question

Is  \frac{a}{b} < 0 ?

(1)  \frac{a^2 }{ b^3} < 0

(2)  a*b^5 < 0

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RaghavKhanna · Answer

St.1 :
a^2/b^3 <0
=> b <0
But 'a' can be >0 or <0, since a^2 is always positive.

So, if a>0, then a/b <0 and if, a<0, then a/b >0

Hence, st.1 is insufficient.

St. 2:
a*b^5 <0
=> either a<0 and b>0, or a>0 and b<0
In both cases a/b <0

=> St. 2 is sufficient.

Answer: B

GMATinsight · Answer

Question: Is a/b < 0?

Statement 1 :  \frac{a^2 }{ b^3} < 0

SInce  a^2  is never Negative therefore  b^3  and hence b must be Negative
But sign of a is unknown hence

NOT SUFFICENT

Statement 2 : a*b^5 < 0

SInce signs of b and b^5 are identical therefore

if  a*b^5 < 0  then  a*b < 0  hence answer to question is DEFINITELY YES

SUFFICIENT

Answer: Option B

GMATWhizTeam · Answer

Solution 
 Step 1: Analyse Question Stem 
 • We need to find if  \frac{a}{b} < 0 
 o Now,  \frac{a}{b} < 0  only if a and b have opposite signs.   
So, we need to determine whether signs of a and b are opposite or not.

Step 2: Analyse Statements Independently (And eliminate options) – AD/BCE 
 Statement 1:   \frac{a^2}{b^3} < 0 
 • Since   a^2  is always positive irrespective of sign of a,
 o So only information we get from this statement is that  b^3 < 0 
  As,  b^3  always has same sign as b ⟹ b is negative. 
o However, we don’t know about the sign of a.  
Hence, statement 1 is NOT sufficient and we can eliminate answer Options A and D.

Statement 2:   a*b^5 < 0 
 • This means, a and  b^5  have opposite signs.
 o Since  b^5   always has same sign as b, we can infer that a and b have opposite signs. 
• Thus,  \frac{a}{b} < 0  
Hence, statement 2 is sufficient.
Thus, the correct answer is  Option B.

vipulshahi · Answer

Is a/b < 0 ?

Statement 1: a^2 / b^3 < 0
a^2 is always positive so it depends on b
b= -ve but we are not sure for the value of "a"
Not Sufficient

Statement 2 : a * b^5 <0
it means both a & b have opposite sign
if A= -ve then b = +ve 
If A = +ve then b = -ve

in any case a/b is always smaller than "0" 
a/b<0
Sufficient

Answer (B)

Archit3110 · Answer

target is a/b<0
i.e either of a or b is -ve value
#1
  \frac{a^2 }{ b^3} < 0 
we can surely say that b is -ve but not sure about a sign so insufficient
#2
 a*b^5 < 0 
either of a or b is -ve so  \frac{a}{b} < 0  is true
sufficient
OPTION B

HoneyLemon · Answer

Ans : B  
 \frac{a}{b} < 0

i.e is a , b opposite sign ?

(1)  \frac{a^2 }{ b^3} < 0 
 b is -ve . But no information about a . So Insufficient

(2)  a*b^5 < 0

a .b^5 will be -ve only if either a <0 or b <0 . 
Hence Sufficient .

sambitspm · Answer

Kindly see the attachment.
We need to see that either one is -ve and other is +ve. Only the second is sufficient
B

bumpbot · Answer

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Is a/b < 0? (1) a^2/b^3 < 0 (2) a*b^5 < 0

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