I think for simple questions people intuitively reach an answer but can’t explain well. I will try to explain my thinking here:
There are 2 conditions we need to learn to answer this question:
I. Is x < 0?
II. Is x > 1?
If either I or II is true, then we have sufficient info. But if I is false, we need to know that II is also false to have sufficient info.
Statement 1 lets us know that condition II (x>1) is false. x is not greater than 1 if the maximum value of x is 1/2.
But we still need to determine whether condition I is false, so statement 1 is insufficient.
Statement 2 gives us the ability to solve for the value of x, so we can test both condition I and condition II with x = 1/2 and see that condition I (x < 0) is false and condition II (x>1) is also false. Since we needed to know either that condition I or condition II is true or that both conditions are false, we have sufficient information with statement 2. Therefore, the answer is b.
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