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Zorluk: KolayInequalities, Absolute Values, and Number Ranges in Data Sufficiency

If xx is a real number, is x3<5|x - 3| < 5?

(1) 1<x<61 < x < 6
(2) x>0x > 0

Which of the following describes the sufficiency of the statements?

  1. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.Cevap
  2. B
    Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
  3. C
    BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
  4. D
    EACH statement ALONE is sufficient.
  5. E
    Statements (1) and (2) TOGETHER are NOT sufficient.

Cevap

Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
The correct choice is the option stating that Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient. Rephrasing x3<5|x - 3| < 5 yields 2<x<8-2 < x < 8. Statement (1) restricts xx to (1,6)(1, 6), which is completely inside (2,8)(-2, 8), guaranteeing a 'Yes' answer. Statement (2) allows values like x=2x = 2 ('Yes') and x=10x = 10 ('No'), so it is not sufficient.

Adım Adım Çözüm

1
Rephrase the target inequality from the stem.
The absolute value inequality x3<5|x - 3| < 5 is equivalent to 5<x3<5-5 < x - 3 < 5. Adding 3 to all parts gives 2<x<8-2 < x < 8. The question asks: 'Is xx strictly between 2-2 and 88?'
Simplifying the stem into a clear range for xx makes evaluating sufficiency straightforward.
2
Evaluate Statement (1): 1<x<61 < x < 6.
Every number in the interval (1,6)(1, 6) is strictly between 2-2 and 88. Thus, the answer to 'Is 2<x<8-2 < x < 8?' is a definitive 'Yes'. Statement (1) alone is sufficient.
Since the entire set of allowed values under statement (1) is a subset of (2,8)(-2, 8), statement (1) provides a conclusive answer.
3
Evaluate Statement (2): x>0x > 0.
If x=2x = 2, then 2<2<8-2 < 2 < 8 is True (Yes). However, if x=10x = 10, then 2<10<8-2 < 10 < 8 is False (No). Because both 'Yes' and 'No' are possible, Statement (2) alone is not sufficient.
A statement is insufficient if it permits values that produce conflicting answers to the target question.

Anahtar Kavram

Absolute Value Inequalities and Range Containment in Data Sufficiency
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