Inequalities, Absolute Values, and Number Ranges in Data Sufficiency

32 questions

Question 21Question

If xx is a real number and x1x \neq -1, is x3x+1<1\frac{|x - 3|}{x + 1} < 1?

(1) 2x1>3|2x - 1| > 3
(2) x(x1)>0x(x - 1) > 0

Show answer & explanation

Answer: Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.

Answer

Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
Rephrasing the question stem shows that x3x+1<1\frac{|x - 3|}{x + 1} < 1 is satisfied when x<1x < -1 or x>1x > 1. Statement (1) solves to x<1x < -1 or x>2x > 2. Since (2,)(2, \infty) is completely contained inside (1,)(1, \infty), every value satisfying Statement (1) yields a definitive YES to the question. Statement (2) solves to x<0x < 0 or x>1x > 1. Choosing x=2x = 2 gives a YES answer, while choosing x=0.5x = -0.5 gives a NO answer. Thus, Statement (1) alone is sufficient, but Statement (2) alone is not sufficient.

Step-by-Step Solution

1
Rephrase the question stem by analyzing cases for the denominator x+1x + 1.
Case 1 (x>1x > -1): x+1>0x + 1 > 0, so x3<x+1    (x+1)<x3<x+1|x - 3| < x + 1 \iff -(x + 1) < x - 3 < x + 1. The right inequality 3<1-3 < 1 is always true, and the left inequality x1<x3-x - 1 < x - 3 simplifies to 2x>2    x>12x > 2 \iff x > 1.
Case 2 (x<1x < -1): x+1<0x + 1 < 0. The numerator x3>0|x - 3| > 0 while the denominator is negative, making the ratio negative, which is always <1< 1.
Combining both cases: The target inequality holds if and only if x<1x < -1 or x>1x > 1.
Rephrasing the stem target simplifies complex absolute value expressions into clear number line intervals.
2
Evaluate Statement (1): 2x1>3|2x - 1| > 3.
2x1>3    2x>4    x>22x - 1 > 3 \implies 2x > 4 \implies x > 2, or 2x1<3    2x<2    x<12x - 1 < -3 \implies 2x < -2 \implies x < -1.
Range: x(,1)(2,)x \in (-\infty, -1) \cup (2, \infty). Every value in this range satisfies x<1x < -1 or x>1x > 1, guaranteeing a definitive YES to the question.
Statement 1 specifies a subset of the valid target range, making it sufficient alone.
3
Evaluate Statement (2): x(x1)>0x(x - 1) > 0.
Range: x<0x < 0 or x>1x > 1. Testing values within this range:
- If x=2x = 2: 2(1)=2>02(1) = 2 > 0, and 232+1=13<1\frac{|2 - 3|}{2 + 1} = \frac{1}{3} < 1 (YES).
- If x=0.5x = -0.5: 0.5(1.5)=0.75>0-0.5(-1.5) = 0.75 > 0, but 0.530.5+1=3.50.5=71\frac{|-0.5 - 3|}{-0.5 + 1} = \frac{3.5}{0.5} = 7 \not< 1 (NO).
Since both YES and NO outcomes are possible, Statement (2) is insufficient.
Finding a counterexample within the statement's solution set proves insufficiency.

Key Concept

Data Sufficiency evaluation for rational expressions containing absolute values and rephrasing inequality ranges.
Estimated Time:2m 0s
Question 22Question

If xx and yy are non-zero real numbers, is xy<1\frac{|x|}{y} < 1?

(1) x2<y2x^2 < y^2
(2) x+y<0x + y < 0

Show answer & explanation

Answer: Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.

Answer

Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
Statement (1) gives x2<y2x^2 < y^2, which means x<y|x| < |y|. If y>0y > 0, y=y|y| = y, so x<y    xy<1|x| < y \implies \frac{|x|}{y} < 1. If y<0y < 0, x>0|x| > 0 implies xy<0<1\frac{|x|}{y} < 0 < 1. Thus, Statement (1) alone yields a definitive 'Yes' and is sufficient. Statement (2) allows x=3,y=1x = -3, y = 1 (yielding a ratio of 3, which is not less than 1) and x=1,y=2x = -1, y = -2 (yielding a ratio of -0.5, which is less than 1), so Statement (2) alone is insufficient.

Step-by-Step Solution

1
Rephrase the target question
The target question asks whether xy<1\frac{|x|}{y} < 1 for non-zero real numbers xx and yy.
Since x>0|x| > 0 for any non-zero real number xx, if y<0y < 0, the ratio xy\frac{|x|}{y} is strictly negative, which is always less than 1. If y>0y > 0, xy<1\frac{|x|}{y} < 1 is equivalent to x<y|x| < y.
2
Evaluate Statement (1): x2<y2x^2 < y^2
Taking the principal square root of both sides gives x<y|x| < |y|.
If y>0y > 0, y=y|y| = y, so x<y|x| < y, which implies xy<1\frac{|x|}{y} < 1 (YES). If y<0y < 0, then yy is negative and x|x| is positive, so xy<0<1\frac{|x|}{y} < 0 < 1 (YES). Since Statement (1) yields a definitive YES in all cases, Statement (1) ALONE is sufficient.
3
Evaluate Statement (2): x+y<0x + y < 0
Test suitable numbers.
Case A: Let x=3x = -3 and y=1y = 1. Then x+y=2<0x + y = -2 < 0, but 31=31\frac{|-3|}{1} = 3 \not< 1 (NO). Case B: Let x=1x = -1 and y=2y = -2. Then x+y=3<0x + y = -3 < 0, and 12=0.5<1\frac{|-1|}{-2} = -0.5 < 1 (YES). Because Statement (2) can yield both YES and NO, Statement (2) ALONE is not sufficient.

Key Concept

Data Sufficiency evaluation of absolute values and algebraic inequalities with unknown signs
Estimated Time:2m 0s
Question 23Question

If xx and yy are non-zero real numbers, is xy<1\frac{x}{y} < 1?

(1) x+y<xy|x + y| < |x - y|
(2) x>yx > y

Which of the following choices correctly describes the sufficiency of the statements?

Show answer & explanation

Answer: Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.

Answer

Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
The correct option states that Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient. Squaring both sides of Statement (1) gives x2+2xy+y2<x22xy+y2x^2 + 2xy + y^2 < x^2 - 2xy + y^2, which simplifies directly to 4xy<04xy < 0, meaning xy<0xy < 0. When two numbers have opposite signs, their quotient xy\frac{x}{y} must be negative, making it strictly less than 1. This provides a definitive 'Yes' answer. Statement (2) gives x>yx > y; if x=3x = 3 and y=2y = 2, 32>1\frac{3}{2} > 1 (No), but if x=1x = 1 and y=2y = -2, 12=0.5<1\frac{1}{-2} = -0.5 < 1 (Yes). Hence Statement (2) is not sufficient.

Step-by-Step Solution

1
Rephrase the target question
The target question asks if xy<1\frac{x}{y} < 1.
Understanding the algebraic condition required for a fraction to be less than 1 helps evaluate given statements.
2
Evaluate Statement (1): x+y<xy|x + y| < |x - y|
Squaring both sides yields (x+y)2<(xy)2    x2+2xy+y2<x22xy+y2    4xy<0    xy<0(x + y)^2 < (x - y)^2 \implies x^2 + 2xy + y^2 < x^2 - 2xy + y^2 \implies 4xy < 0 \implies xy < 0.
Since both sides of the inequality are non-negative distance expressions, squaring preserves the inequality sign.
3
Determine the sufficiency of Statement (1)
Since xy<0xy < 0, xx and yy must have opposite signs. Therefore, xy\frac{x}{y} is negative, which means xy<0<1\frac{x}{y} < 0 < 1. This gives a definitive 'Yes' to the question.
Any negative number is strictly less than 1, so Statement (1) alone is sufficient.
4
Evaluate Statement (2): x>yx > y
If x=3x = 3 and y=2y = 2, then x>yx > y and xy=1.5>1\frac{x}{y} = 1.5 > 1 (No). If x=1x = 1 and y=2y = -2, then x>yx > y and xy=0.5<1\frac{x}{y} = -0.5 < 1 (Yes).
Testing cases with positive vs. negative denominators shows that Statement (2) leads to both 'Yes' and 'No' answers.
5
Determine the sufficiency of Statement (2) and select the overall answer choice
Statement (2) alone is not sufficient. Therefore, Statement (1) alone is sufficient, but statement (2) alone is not sufficient.
Only Statement (1) provides a definitive answer to the question stem.

Key Concept

Distance interpretation of absolute values and algebraic rephrasing of inequalities involving quotient sign analysis.
Estimated Time:2m 0s
Question 24Question

If xx is a real number, is x+2+x48|x + 2| + |x - 4| \le 8?

(1) x14|x - 1| \le 4
(2) x2x60x^2 - x - 6 \le 0

Show answer & explanation

Answer: EACH statement ALONE is sufficient.

Answer

Each statement alone is sufficient.
Rephrasing the question stem shows that x+2+x48|x + 2| + |x - 4| \le 8 is equivalent to 3x5-3 \le x \le 5. Statement (1) gives 3x5-3 \le x \le 5, which directly yields a definitive 'Yes'. Statement (2) gives 2x3-2 \le x \le 3, which is a subset of [3,5][-3, 5], so any value of xx satisfying Statement (2) must also satisfy 3x5-3 \le x \le 5, also yielding a definitive 'Yes'. Thus, each statement alone is sufficient.

Step-by-Step Solution

1
Rephrase the question stem target by analyzing critical points x=2x = -2 and x=4x = 4 for x+2+x48|x + 2| + |x - 4| \le 8.
The target inequality x+2+x48|x + 2| + |x - 4| \le 8 simplifies to the range 3x5-3 \le x \le 5.
For x4x \ge 4: (x+2)+(x4)8    2x28    x5(x + 2) + (x - 4) \le 8 \implies 2x - 2 \le 8 \implies x \le 5, giving [4,5][4, 5]. For 2x<4-2 \le x < 4: (x+2)+(4x)=68(x + 2) + (4 - x) = 6 \le 8, which is true for all x[2,4)x \in [-2, 4). For x<2x < -2: (x2)+(4x)8    22x8    2x6    x3(-x - 2) + (4 - x) \le 8 \implies 2 - 2x \le 8 \implies -2x \le 6 \implies x \ge -3, giving [3,2)[-3, -2). Combining all intervals gives 3x5-3 \le x \le 5.
2
Evaluate Statement (1): x14|x - 1| \le 4.
4x14    3x5-4 \le x - 1 \le 4 \implies -3 \le x \le 5.
Statement (1) states that xx is precisely in the range [3,5][-3, 5]. This provides a definitive 'Yes' answer to the question 'Is 3x5-3 \le x \le 5?'. Thus, Statement (1) alone is sufficient.
3
Evaluate Statement (2): x2x60x^2 - x - 6 \le 0.
(x3)(x+2)0    2x3(x - 3)(x + 2) \le 0 \implies -2 \le x \le 3.
Since [2,3][-2, 3] is entirely contained within [3,5][-3, 5], every value of xx satisfying Statement (2) automatically satisfies 3x5-3 \le x \le 5. This yields a definitive 'Yes' to the question. Thus, Statement (2) alone is sufficient.
4
Combine evaluations of Statement (1) and Statement (2).
Each statement alone is sufficient.
Because both statements independently provide enough information to give a definitive 'Yes' answer, the correct answer choice is that each statement alone is sufficient.

Key Concept

Absolute Value Distance Interpretation and Subset Range Sufficiency
Question 25Question

If mm and nn are real numbers, is m2<n2m^2 < n^2?

(1) m+n<0|m| + n < 0
(2) m+n>0m + n > 0

Show answer & explanation

Answer: Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.

Answer

Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
Rephrased, the question asks whether m<n|m| < |n|. Evaluating the first condition gives n<mn < -|m|, which shows that nn must be negative and its absolute value n=n|n| = -n must be strictly greater than m|m|. Hence, m2<n2m^2 < n^2 is definitely true. Evaluating the second condition allows both m=2,n=5m=2, n=5 (where m2<n2m^2 < n^2) and m=5,n=2m=5, n=2 (where m2>n2m^2 > n^2), making it insufficient. Therefore, the first condition alone is sufficient while the second condition alone is not.

Step-by-Step Solution

1
Rephrase the target question stem m2<n2m^2 < n^2.
The target condition m2<n2m^2 < n^2 is equivalent to m2<n2|m|^2 < |n|^2, which is true if and only if m<n|m| < |n|.
Since both m2m^2 and n2n^2 are non-negative, taking the square root of both sides preserves the inequality order for non-negative magnitudes.
2
Evaluate Statement (1): m+n<0|m| + n < 0.
Rearranging gives n<mn < -|m|. Since m0|m| \ge 0, this implies nn is strictly negative. Taking absolute values of both sides of n<mn < -|m| gives n=n>m|n| = -n > |m|. Therefore, n>m|n| > |m|, which means n2>m2n^2 > m^2 or m2<n2m^2 < n^2.
Statement (1) yields a definitive 'Yes' to the target question. Thus, Statement (1) alone is sufficient.
3
Evaluate Statement (2): m+n>0m + n > 0.
Case 1: Let m=2m = 2 and n=5n = 5. Then 2+5=7>02 + 5 = 7 > 0, and 22=4<25=522^2 = 4 < 25 = 5^2 (Yes). Case 2: Let m=5m = 5 and n=2n = 2. Then 5+2=7>05 + 2 = 7 > 0, but 52=25>4=225^2 = 25 > 4 = 2^2 (No).
Because Statement (2) allows both 'Yes' and 'No' outcomes, Statement (2) alone is not sufficient.

Key Concept

Data Sufficiency evaluation of absolute values and algebraic inequalities
Question 26Question

If xx and yy are real numbers such that x0x \neq 0, is xyx>1\frac{|x - y|}{x} > 1?

(1) x<0x < 0
(2) y<0y < 0

Show answer & explanation

Answer: Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.

Answer

Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
Statement (1) tells us x<0x < 0. Since xy0|x - y| \ge 0 for all real numbers, dividing a non-negative numerator by a negative denominator guarantees that xyx0\frac{|x - y|}{x} \le 0. Consequently, xyx\frac{|x - y|}{x} can never be greater than 11, giving a definitive 'No' answer to the question. Because Statement (1) provides a single definitive answer, it is sufficient. Statement (2) tells us y<0y < 0, but leaves the sign and value of xx unconstrained. Choosing x=1x = -1 with y=2y = -2 gives a value of 1-1 (answering 'No'), while choosing x=1x = 1 with y=2y = -2 gives a value of 33 (answering 'Yes'). Since Statement (2) allows both 'Yes' and 'No' outcomes, it is not sufficient. Thus, the option stating that Statement (1) alone is sufficient while Statement (2) alone is not sufficient is correct.

Step-by-Step Solution

1
Analyze the target question stem and algebraic constraints.
We are asked whether xyx>1\frac{|x - y|}{x} > 1. Notice that for any real numbers xx and yy, the absolute value in the numerator xy0|x - y| \ge 0. The sign of the denominator xx determines the sign of the entire quotient.
Understanding the algebraic behavior of non-negative numerators over signed denominators simplifies statement evaluation.
2
Evaluate Statement (1): x<0x < 0.
Since xy0|x - y| \ge 0 and x<0x < 0, the ratio xyx\frac{|x - y|}{x} is a non-negative number divided by a negative number. Thus, xyx0\frac{|x - y|}{x} \le 0. Since a number 0\le 0 can never be greater than 11, the answer to the question is a definitive 'No'. A definitive 'No' means the statement IS sufficient.
In Data Sufficiency, any statement that allows us to answer the question with a single, unambiguous 'Yes' or 'No' is sufficient.
3
Evaluate Statement (2): y<0y < 0.
Test values for xx while holding y<0y < 0 (e.g., y=2y = -2). If x=1x = -1, then 1(2)1=11=11\frac{|-1 - (-2)|}{-1} = \frac{1}{-1} = -1 \ngtr 1 (Answer: No). If x=1x = 1, then 1(2)1=31=3>1\frac{|1 - (-2)|}{1} = \frac{3}{1} = 3 > 1 (Answer: Yes). Because both 'Yes' and 'No' are possible, Statement (2) is not sufficient.
Getting conflicting answers from permissible test cases proves a statement is insufficient.

Key Concept

Definitive Yes/No logic and sign properties of absolute value quotients in Data Sufficiency
Question 27Question

If mm is a real number, is m22m3<5|m^2 - 2m - 3| < 5?

(1) m2<3|m - 2| < 3
(2) m+1<4|m + 1| < 4

Show answer & explanation

Answer: BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

Answer

BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
Rephrasing the question stem requires solving m22m3<5|m^2 - 2m - 3| < 5. This breaks down into 5<m22m3<5-5 < m^2 - 2m - 3 < 5. The left inequality m22m+2>0m^2 - 2m + 2 > 0 holds for all real numbers because its discriminant is negative and the quadratic opens upward. The right inequality m22m8<0m^2 - 2m - 8 < 0 factors as (m4)(m+2)<0(m - 4)(m + 2) < 0, giving the target range 2<m<4-2 < m < 4.

Evaluating the first statement gives m2<3    1<m<5|m - 2| < 3 \implies -1 < m < 5. This interval extends past 4 (e.g., m=4.5m = 4.5 yields a 'No', while m=1m = 1 yields a 'Yes'), so the first statement alone is not sufficient.

Evaluating the second statement gives m+1<4    5<m<3|m + 1| < 4 \implies -5 < m < 3. This interval extends past 2-2 (e.g., m=4m = -4 yields a 'No', while m=1m = 1 yields a 'Yes'), so the second statement alone is not sufficient.

Combining both statements requires taking the intersection of 1<m<5-1 < m < 5 and 5<m<3-5 < m < 3, which gives 1<m<3-1 < m < 3. Since every number in the range (1,3)(-1, 3) lies strictly between 2-2 and 44, the target condition is guaranteed to be true. Therefore, both statements together are sufficient, but neither statement alone is sufficient.

Step-by-Step Solution

1
Rephrase the target question stem algebraically.
The target inequality m22m3<5|m^2 - 2m - 3| < 5 is equivalent to 5<m22m3<5-5 < m^2 - 2m - 3 < 5. Solving the upper bound gives m22m8<0    (m4)(m+2)<0    2<m<4m^2 - 2m - 8 < 0 \implies (m - 4)(m + 2) < 0 \implies -2 < m < 4. The lower bound m22m3>5    m22m+2>0    (m1)2+1>0m^2 - 2m - 3 > -5 \implies m^2 - 2m + 2 > 0 \implies (m - 1)^2 + 1 > 0 is true for all real mm. Thus, the question simplifies to: 'Is 2<m<4-2 < m < 4?'
Simplifying the target stem establishes the exact numerical interval required to yield a definitive 'Yes' or 'No' response.
2
Evaluate Statement (1) independently.
Statement (1) states m2<3    3<m2<3    1<m<5|m - 2| < 3 \implies -3 < m - 2 < 3 \implies -1 < m < 5. If m=1m = 1, 2<1<4-2 < 1 < 4 (Yes). However, if m=4.5m = 4.5, mm is not in (2,4)(-2, 4) (No). Since Statement (1) allows both 'Yes' and 'No' outcomes, it is NOT sufficient.
A statement is sufficient only if every value in its allowed range produces the same answer to the rephrased question.
3
Evaluate Statement (2) independently.
Statement (2) states m+1<4    4<m+1<4    5<m<3|m + 1| < 4 \implies -4 < m + 1 < 4 \implies -5 < m < 3. If m=1m = 1, 2<1<4-2 < 1 < 4 (Yes). However, if m=4m = -4, mm is not in (2,4)(-2, 4) (No). Thus, Statement (2) is NOT sufficient.
Checking boundary values reveals that Statement (2) allows values outside the required interval.
4
Evaluate Statement (1) and Statement (2) together.
Combining Statement (1) range (1<m<5)(-1 < m < 5) and Statement (2) range (5<m<3)(-5 < m < 3) requires taking their intersection: 1<m<3-1 < m < 3. Since every value in (1,3)(-1, 3) satisfies 2<m<4-2 < m < 4, the answer to the question is a definitive 'Yes'.
The intersection of the two ranges falls strictly inside the target range, guaranteeing sufficiency.

Key Concept

Data Sufficiency range evaluation for quadratic absolute value inequalities
Estimated Time:2m 0s
Question 28Question

If xx is a real number, is x5<x+1|x - 5| < x + 1?

(1) x26x+8<0x^2 - 6x + 8 < 0
(2) x3<2|x - 3| < 2

Which of the following choices correctly describes the sufficiency of the statements?

Show answer & explanation

Answer: Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.

Answer

Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
The question target x5<x+1|x - 5| < x + 1 simplifies directly to x>2x > 2. Statement (1) bounds xx to 2<x<42 < x < 4, which guarantees that x>2x > 2 is always true, providing a definitive 'Yes'. Statement (2) bounds xx to 1<x<51 < x < 5, allowing values such as 1.51.5 (where x>2x > 2 is false) and 33 (where x>2x > 2 is true), which is insufficient. Therefore, Statement (1) alone is sufficient, but Statement (2) alone is not sufficient.

Step-by-Step Solution

1
Rephrase the question stem by simplifying the absolute value inequality x5<x+1|x - 5| < x + 1.
The inequality holds if and only if (x+1)<x5<x+1-(x + 1) < x - 5 < x + 1. Solving x1<x5-x - 1 < x - 5 yields 2x>42x > 4, or x>2x > 2. Solving x5<x+1x - 5 < x + 1 yields 5<1-5 < 1, which is always true. Thus, the question rephrases to: 'Is x>2x > 2?'
Simplifying absolute value conditions in the stem reduces complex expressions to a single target range.
2
Evaluate Statement (1): x26x+8<0x^2 - 6x + 8 < 0.
Factoring gives (x2)(x4)<0(x - 2)(x - 4) < 0, which yields the range 2<x<42 < x < 4. For any value of xx in (2,4)(2, 4), xx is strictly greater than 22. This gives a definitive 'Yes' to the rephrased question.
Since every value satisfying Statement (1) satisfies x>2x > 2, Statement (1) alone is sufficient.
3
Evaluate Statement (2): x3<2|x - 3| < 2.
Unfolding the absolute value gives 2<x3<2-2 < x - 3 < 2, or 1<x<51 < x < 5. If x=1.5x = 1.5, then x>2x > 2 is false ('No'). If x=3x = 3, then x>2x > 2 is true ('Yes'). Because both 'Yes' and 'No' answers are possible, Statement (2) is not sufficient.
Statement (2) permits values both above and below the threshold of 2.

Key Concept

Question Stem Rephrasing for Absolute Value Inequalities
Estimated Time:2m 0s
Question 29Question

If kk is a real number such that k1k \neq -1, is k3k+1<1\frac{|k - 3|}{k + 1} < 1?

(1) k>1|k| > 1
(2) k22k3>0k^2 - 2k - 3 > 0

Show answer & explanation

Answer: EACH statement ALONE is sufficient.

Answer

EACH statement ALONE is sufficient.
Rephrasing the question stem shows that k3k+1<1\frac{|k - 3|}{k + 1} < 1 holds whenever k<1k < -1 or k>1k > 1. Statement (1) gives k<1k < -1 or k>1k > 1, yielding a definitive YES. Statement (2) gives k<1k < -1 or k>3k > 3, which is a subset of k<1k < -1 or k>1k > 1, also yielding a definitive YES. Thus, each statement alone is sufficient.

Step-by-Step Solution

1
Rephrase the question stem target inequality
The target inequality k3k+1<1\frac{|k - 3|}{k + 1} < 1 is satisfied if and only if k<1k < -1 or k>1k > 1.
Analyze by cases depending on the sign of the denominator k+1k + 1.
- Case 1: k+1<0    k<1k + 1 < 0 \implies k < -1. The denominator is negative and the numerator k30|k - 3| \ge 0, so k3k+10<1\frac{|k - 3|}{k + 1} \le 0 < 1 is always true for all k<1k < -1.
- Case 2: k+1>0    k>1k + 1 > 0 \implies k > -1. Multiplying by k+1>0k + 1 > 0 yields k3<k+1|k - 3| < k + 1, which expands to (k+1)<k3<k+1-(k + 1) < k - 3 < k + 1. The left boundary k1<k3-k - 1 < k - 3 reduces to 2k>2    k>12k > 2 \implies k > 1. The right boundary k3<k+1    3<1k - 3 < k + 1 \implies -3 < 1 is universally true. Thus for k>1k > -1, the condition holds when k>1k > 1.
Combining both cases, the inequality holds whenever k<1k < -1 or k>1k > 1.
2
Evaluate Statement (1)
Statement (1) alone is SUFFICIENT.
Statement (1) states k>1|k| > 1, which unwraps to k<1k < -1 or k>1k > 1. This matches the target condition exactly. For every value of kk satisfying this statement, the answer to the stem question is a definitive YES.
3
Evaluate Statement (2)
Statement (2) alone is SUFFICIENT.
Statement (2) states k22k3>0k^2 - 2k - 3 > 0, which factors as (k3)(k+1)>0(k - 3)(k + 1) > 0. Solving gives k<1k < -1 or k>3k > 3.
- If k<1k < -1, it falls into the left target region k<1k < -1.
- If k>3k > 3, it falls into the right target region k>1k > 1.
In all cases allowed by Statement (2), the answer to the stem question is a definitive YES.

Key Concept

Inequalities with absolute values and variables in the denominator require case analysis based on the denominator's sign.
Question 30Question

If rr is a real number, is r3<rr^3 < r?

(1) r0.5<0.5|r - 0.5| < 0.5
(2) r<1|r| < 1

Which of the following choices correctly describes the sufficiency of the statements?

Show answer & explanation

Answer: Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.

Answer

Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
Rephrasing r3<rr^3 < r shows that the inequality holds true if and only if r<1r < -1 or 0<r<10 < r < 1. Statement (1) bounds rr precisely within the interval (0,1)(0, 1), ensuring a definitive 'Yes' answer. Statement (2) defines the range (1,1)(-1, 1), which includes values where the inequality holds (such as 0.50.5) and values where it fails (such as 0.5-0.5), making it insufficient.

Step-by-Step Solution

1
Rephrase the target inequality algebraically.
The inequality r3<rr^3 < r rearranges to r3r<0r^3 - r < 0, which factors as r(r1)(r+1)<0r(r - 1)(r + 1) < 0.
Simplifying the stem isolates the specific intervals on the number line where the statement holds true.
2
Determine the valid number ranges for the rephrased question.
The expression r(r1)(r+1)r(r - 1)(r + 1) is strictly negative when r<1r < -1 or when 0<r<10 < r < 1.
Testing sign changes across key boundary points (r=1r = -1, r=0r = 0, r=1r = 1) identifies the target ranges.
3
Evaluate Statement (1): r0.5<0.5|r - 0.5| < 0.5.
This absolute value inequality expands to 0.5<r0.5<0.5-0.5 < r - 0.5 < 0.5, which simplifies to 0<r<10 < r < 1.
Since every value in the range 0<r<10 < r < 1 satisfies r3<rr^3 < r, Statement (1) yields a definitive 'Yes'. Thus, Statement (1) alone is sufficient.
4
Evaluate Statement (2): r<1|r| < 1.
This absolute value inequality simplifies to 1<r<1-1 < r < 1.
If r=0.5r = 0.5, then r3=0.125<0.5r^3 = 0.125 < 0.5 (Yes). However, if r=0.5r = -0.5, then r3=0.125>0.5r^3 = -0.125 > -0.5 (No). Because Statement (2) allows both 'Yes' and 'No' outcomes, it is not sufficient.

Key Concept

Data Sufficiency evaluation of cubic inequalities and absolute value range constraints
Question 31Question

If xx is a real number, is x3x>x21|x^3 - x| > x^2 - 1?

(1) x1>0|x - 1| > 0
(2) x+2<1|x + 2| < 1

Show answer & explanation

Answer: Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.

Answer

Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
The correct option is the one stating that Statement (2) alone is sufficient, but Statement (1) alone is not sufficient. Simplifying the stem target x3x>x21|x^3 - x| > x^2 - 1 into xx21>x21|x||x^2 - 1| > x^2 - 1 reveals that the inequality holds for every real number except x=1x = 1 and x=1x = -1 (where both sides equal zero). Statement (1) states x1>0|x - 1| > 0, meaning x1x \neq 1, but it permits x=1x = -1, which yields a 'No' answer, making Statement (1) insufficient. Statement (2) states x+2<1|x + 2| < 1, which expands to 3<x<1-3 < x < -1. Because this interval strictly excludes both x=1x = -1 and x=1x = 1, every value of xx in this range satisfies the stem inequality, yielding a definitive 'Yes'.

Step-by-Step Solution

1
Rephrase the question stem target algebraically.
The target inequality x3x>x21|x^3 - x| > x^2 - 1 simplifies to x(x21)>x21|x(x^2 - 1)| > x^2 - 1, which is equivalent to xx21>x21|x| \cdot |x^2 - 1| > x^2 - 1.
Factoring allows analysis of the critical values where x21=0x^2 - 1 = 0.
2
Analyze the conditions under which xx21>x21|x| \cdot |x^2 - 1| > x^2 - 1 holds true.
Case 1: If x21=0x^2 - 1 = 0 (meaning x=1x = 1 or x=1x = -1), LHS = 00 and RHS = 00, giving 0>00 > 0, which is FALSE. Case 2: If x21<0x^2 - 1 < 0 (meaning 1<x<1-1 < x < 1), LHS is positive and RHS is negative, so non-negative > negative is TRUE. Case 3: If x21>0x^2 - 1 > 0 (meaning x>1x > 1 or x<1x < -1), dividing both sides by x21>0x^2 - 1 > 0 yields x>1|x| > 1, which is TRUE. Thus, the inequality holds for ALL real numbers EXCEPT x=1x = 1 and x=1x = -1. The question simplifies to: Is x1x \neq 1 and x1x \neq -1?
Simplifying the target reveals that the inequality is true everywhere except at the two boundary roots x=1x = 1 and x=1x = -1.
3
Evaluate Statement (1): x1>0|x - 1| > 0.
This implies x1x \neq 1. However, xx could equal 1-1. If x=1x = -1, 11=2>0|-1 - 1| = 2 > 0 is satisfied, but (1)3(1)=0|(-1)^3 - (-1)| = 0 and (1)21=0(-1)^2 - 1 = 0, giving 0>00 > 0 (NO). If x=2x = 2, 21=1>0|2 - 1| = 1 > 0 is satisfied, and 82=6>3|8 - 2| = 6 > 3 (YES). Since both 'Yes' and 'No' are possible, Statement (1) is NOT sufficient.
Statement (1) rules out x=1x = 1 but permits x=1x = -1.
4
Evaluate Statement (2): x+2<1|x + 2| < 1.
Solving the absolute value inequality gives 1<x+2<1-1 < x + 2 < 1, which simplifies to 3<x<1-3 < x < -1. In this range, xx cannot be 11 or 1-1 because the upper boundary is strictly less than 1-1. Thus, for all x(3,1)x \in (-3, -1), x1x \neq 1 and x1x \neq -1 is guaranteed, yielding a definitive 'YES'. Statement (2) is SUFFICIENT.
The open interval (3,1)(-3, -1) excludes both x=1x = -1 and x=1x = 1.

Key Concept

Question Stem Simplification with Absolute Value Inequalities
Estimated Time:2m 0s
Question 32Question

If aa and bb are non-zero real numbers, is a+b>ab|a + b| > |a - b|?

(1) a+2b<a2b|a + 2b| < |a - 2b|
(2) ab+ba<0\frac{|a|}{b} + \frac{|b|}{a} < 0

Show answer & explanation

Answer: Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.

Answer

Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
Rephrasing the question stem by squaring both sides gives a+b2>ab2    (a+b)2>(ab)2    4ab>0    ab>0|a + b|^2 > |a - b|^2 \iff (a + b)^2 > (a - b)^2 \iff 4ab > 0 \iff ab > 0. Statement (1) simplifies similarly by squaring both sides to (a+2b)2<(a2b)2    8ab<0    ab<0(a + 2b)^2 < (a - 2b)^2 \iff 8ab < 0 \iff ab < 0. Since ab<0ab < 0 guarantees that ab>0ab > 0 is false, Statement (1) produces a definitive 'No' and is therefore sufficient. Statement (2) is satisfied when both aa and bb are negative (giving ab>0ab > 0, a 'Yes' answer) as well as when aa and bb have opposite signs with a>b|a| > |b| (giving ab<0ab < 0, a 'No' answer). Because Statement (2) permits both outcomes, it is insufficient.

Step-by-Step Solution

1
Rephrase the question stem target using algebraic properties of absolute values.
Squaring both non-negative sides of a+b>ab|a + b| > |a - b| yields (a+b)2>(ab)2    a2+2ab+b2>a22ab+b2    4ab>0    ab>0(a + b)^2 > (a - b)^2 \implies a^2 + 2ab + b^2 > a^2 - 2ab + b^2 \implies 4ab > 0 \implies ab > 0. The question asks: 'Is ab>0ab > 0?'
Simplifying the stem target into a fundamental sign constraint (ab>0ab > 0) prevents algebraic errors during statement evaluation.
2
Evaluate Statement (1): a+2b<a2b|a + 2b| < |a - 2b|.
Squaring both sides yields (a+2b)2<(a2b)2    a2+4ab+4b2<a24ab+4b2    8ab<0    ab<0(a + 2b)^2 < (a - 2b)^2 \implies a^2 + 4ab + 4b^2 < a^2 - 4ab + 4b^2 \implies 8ab < 0 \implies ab < 0.
Since ab<0ab < 0, abab cannot be greater than 00. This yields a definitive 'No' to the question 'Is ab>0ab > 0?'. A definitive 'No' is sufficient.
3
Evaluate Statement (2): ab+ba<0\frac{|a|}{b} + \frac{|b|}{a} < 0.
Combine the fractions: aa+bbab<0\frac{a|a| + b|b|}{ab} < 0. Test specific cases:
- Case A: a=2,b=2    22+22=2<0a = -2, b = -2 \implies \frac{|-2|}{-2} + \frac{|-2|}{-2} = -2 < 0. Here ab=4>0ab = 4 > 0 (Answer: YES).
- Case B: a=3,b=1    31+13=3+13=83<0a = 3, b = -1 \implies \frac{|3|}{-1} + \frac{|-1|}{3} = -3 + \frac{1}{3} = -\frac{8}{3} < 0. Here ab=3<0ab = -3 < 0 (Answer: NO).
Since Statement (2) allows both a 'Yes' and a 'No' response to whether ab>0ab > 0, Statement (2) alone is not sufficient.

Key Concept

Data Sufficiency Yes/No decision logic combined with distance and squaring properties of absolute value inequalities.
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Inequalities, Absolute Values, and Number Ranges in Data Sufficiency Practice Questions — GMAT — Page 2 | Examkin