If c 0 and ab/c

Question

If c ≠ 0 and  \frac{(a*b)}{c}<0 , is  \frac{a}{c}<0  ?

(1) a < 0

(2) b < 0

GMATinsight · Answer

Given: ab/c < 0 i.e. two of three variables have same sign and third one has opposite sign

Question: Is a/c < 0?  
i.e.   Question: Do a and c have opposite signs?

Statement 1 : a < 0 
It doesn't help because we are still unaware about signs of b and c hence
 NOT SUFFICIENT

Statement 2 : b < 0 
It doesn't help because we are still unaware about signs of a and c hence
 NOT SUFFICIENT

COmbining the statements

a < 0 and b < 0 i.e. c > 0
i.e. a/c < 0 (YES)
 SUFFICIENT

Answer: Option C

Nabneet · Answer

c
eq{0}

ab/c <0

a= - ,b= -, c=-
a= + ,b= -, c=+
a= + ,b= +, c= -
a= - ,b= +, c=+

1. a<0
a= - ,b= -, c=-
a= - ,b= +, c=+

Not Sufficient

2. b<0
a= - ,b= -, c=-
a= + ,b= -, c=+

ab/c >0

Sufficient.

Answer: B

Nabneet · Answer

I suppose u missed the case where all three are negative.
a= - ,b= -, c=- ; ab/c <0

If c 0 and ab/c < 0, is a/c < 0 ?