Hi,

Just to add more clarity,

Question: Is I a-b| < |a| + |b| ?

The above modulus expression will be true (answer “Yes” to the question) only if “a” and “b” have same signs.

Say for an example, if a =2 and b= 3,

1 < 5

Say if both are negative, a = -2 and b = -3

1 < 5

For “a” and “b” different signs then the above modulus expression won’t hold true (answer “NO” to the question).

Say for an example, if a = -2 and b = 3

5 = 5

Statement I is sufficient:

a/b < 0

So, a and b should have alternate signs.

So the answer to the question would be “NO”. A definite NO, so sufficient. Because it always be equal if they have different signs.

So sufficient.

Statement II is insufficient:

a^2 * b < 0

Since a^2 is positive number, b has to be negative.

But only thing here, a^2 is positive we cant say whether “a” is positive or negative.

If “a” is positive and since b is negative, they have alternate signs, so the answer to the question would be “NO”.

But if “a” is negative and since b is negative, they have same signs, so the answer to the question would be “YES”.

So, Statement II is insufficient.

So, the answer is A(I alone sufficient)

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GMAT Mentors