Is a=b?

eccentric wrote:Is a=b?
1. a+b < 0
2. ab < 0

i got for E

statement 1

assume a = -5 and b = 2

a + b <0 , -5 +2 <0...... hence insufficent

statement 2

a= -5 and b = 2

ab<0 ; -10 <0..............hence insufficient

combining 1 and 2 also doesnt help..

hence E

hope that helps

PS: My 500th post

sudhir3127 wrote:

eccentric wrote:Is a=b?
1. a+b < 0
2. ab < 0

i got for E

statement 1

assume a = -5 and b = 2

a + b <0 , -5 +2 <0...... hence insufficent

statement 2

a= -5 and b = 2

ab<0 ; -10 <0..............hence insufficient

combining 1 and 2 also doesnt help..

hence E

hope that helps

PS: My 500th post

You only demonstrate that a statement is insufficient if you get BOTH a "yes" answer AND a "no" answer. You're only partway done!

(1) a + b < 0

We can certainly pick the numbers you chose: a = -5 and b = 2

Now we ask the original question: is -5 = 2? NO.

To show that (1) is insufficient, we also need to get a "yes" answer.

We can also pick a = -2 and b = -2, since -2 + (-2) < 0

Is -2 = -2? YES.

Now that we have both a yes and a no, we can say that (1) is insufficent.

(2) ab < 0

Well, if the product of two numbers is negative, one MUST be negative and one MUST be positive.

If our numbers have different signs, is a = b? Definitely NOT. Therefore, (2) is sufficient.

(2) is sufficient, (1) is not: choose (B).

Remember, for yes/no data sufficiency questions, a definite "yes" OR a definite "no" is sufficient.