
Question: Is |x - 1| < 1?
“Is |x - 1| < 1?” – is a topic of the GMAT Quantitative reasoning section of GMAT. This question has been taken f0rom the book "GMAT Quantitative Review". GMAT Quant section consists of a total of 31 questions. GMAT Data Sufficiency questions consist of a problem statement followed by two factual statements. GMAT data sufficiency comprises 15 questions which are two-fifths of the total 31 GMAT quant questions.
Answer:
Approach Solution 1:
Considering S1, we have \((x-1)^2\leq1\)
Since both the sides of the inequality are non-negative then we can take square root from both parts: |x – 1| \(\leq\)1, so |x – 1| can be less than 1 (answer YES), as well as equal to 1, for x = 2 or x = 0 (answer NO)
Hence, this statement is Not Sufficient.
Notice that |x – 1| \(\leq\)1, means 0 x\(\leq\) 2
Now consider S2, we have \(x^2-1 > 0\)
Rearrange \(x^2>1\)
Again, since both sides of the inequality are non-negative then we can take square root from both parts: |x| > 1.
If x = 1.5 then the answer is YES but if x = 2 then the answer is NO.
Hence, this statement is Not Sufficient.
(1) + (2) x = 1.5 and x = 2 satisfy both the statements and give different answers to the questions.
Hence, this statement is Not Sufficient.
Correct Answer: E
Approach Solution 2:
There can be two scenarios for the main statement
Here, - x + 1 < 1
-x < 0
x > 0
0 < x < 1= x value should be in the range
b) x – 1 > 0; x > 1
x – 1 < 1
x < 2
1 < x < 2 = another range of x value
Now let’s look at the two options
1)\((x-1)^2\leq1\)
(x – 1)\(\leq\) 1; x – 1\(\leq\) -1
x \(\leq\)2 and x\(\leq\) -2
Doesn’t satisfy the range
Hence, this statement is Not Sufficient.
2)\(x^2-1 > 0\)
\(x^2>1\)
It can take any positive value and doesn’t satisfy the range.
Correct Answer: E
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