Data Sufficiency

263 soru

Soru 41Soru

If xx and yy are positive integers, is the product xyxy divisible by 4?

(1) xx is divisible by 4.
(2) x+yx + y is an odd integer.

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

Cevap

Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
The correct answer is that Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient. Statement (1) establishes that xx is a multiple of 4, so any integer product xyxy must also be a multiple of 4. Statement (2) only guarantees that one of xx or yy is even, which is not enough to determine if the product has two factors of 2.

Adım Adım Çözüm

1
Analyze the question stem target
We need to determine whether xyxy is divisible by 4, given that xx and yy are positive integers.
Establishing integer constraints ensures we evaluate divisibility conditions properly.
2
Evaluate Statement (1) independently
If xx is divisible by 4, then x=4kx = 4k for some positive integer kk. Then xy=(4k)y=4(ky)xy = (4k)y = 4(ky), which is divisible by 4. This gives a definitive YES.
Multiplying any multiple of 4 by an integer results in a multiple of 4. Therefore, Statement (1) alone is sufficient.
3
Evaluate Statement (2) independently
If x+yx + y is odd, one integer is even and the other is odd. Case 1: If x=4x = 4 and y=1y = 1, x+y=5x+y=5 (odd) and xy=4xy = 4 (divisible by 4 -> YES). Case 2: If x=2x = 2 and y=3y = 3, x+y=5x+y=5 (odd) and xy=6xy = 6 (not divisible by 4 -> NO).
Since Statement (2) yields both YES and NO outcomes, it alone is not sufficient.

Anahtar Kavram

Divisibility and Parity Rules in Data Sufficiency
Soru 42Soru

What is the value of the real number kk?

(1) 4k8=124k - 8 = 12
(2) k2=25k^2 = 25

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

Cevap

Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
Solving Statement (1) gives 4k=204k = 20, which simplifies to k=5k = 5. Because this is a single, unique value, Statement (1) alone is sufficient. Statement (2) gives k2=25k^2 = 25, which has two valid solutions (k=5k = 5 or k=5k = -5). Without additional constraints, Statement (2) alone is not sufficient to determine a single value for kk. Therefore, Statement (1) alone is sufficient, but Statement (2) alone is not sufficient.

Adım Adım Çözüm

1
Evaluate Statement (1) independently
4k8=12    4k=20    k=54k - 8 = 12 \implies 4k = 20 \implies k = 5
Solving the linear equation gives a single, unique value for kk. Thus, Statement (1) alone is sufficient.
2
Evaluate Statement (2) independently
k2=25    k=5k^2 = 25 \implies k = 5 or k=5k = -5
Taking the square root yields two distinct possible values for kk. Because kk cannot be uniquely determined, Statement (2) alone is not sufficient.
3
Select the Data Sufficiency decision key
Statement (1) is sufficient, but Statement (2) is not.
This corresponds to the standard option where Statement (1) alone is sufficient.

Anahtar Kavram

Linear vs. Quadratic Degree Sufficiency in Data Sufficiency
Soru 43Soru

In Data Sufficiency analysis, for any non-zero real numbers xx and yy with xy|x| \neq |y|, the target question 'Is x2y2xy>0\frac{x^2 - y^2}{xy} > 0?' is algebraically equivalent to the rephrased target question 'Do xx and yy have opposite signs if and only if x<y|x| < |y|?'

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Cevap: True

Cevap

The statement is TRUE.
The quotient x2y2xy\frac{x^2 - y^2}{xy} is positive in two distinct cases: when x,yx, y have the same sign and x>y|x| > |y| (in which case both 'opposite signs' and 'x<y|x| < |y|' are false, making their biconditional true), or when x,yx, y have opposite signs and x<y|x| < |y| (in which case both components are true, making their biconditional true). In cases where the quotient is negative, the biconditional evaluates to false. Thus, the rephrased target question is logically and algebraically identical to the original target question.

Adım Adım Çözüm

1
Analyze the sign conditions required for the fraction to be positive.
x2y2xy>0\frac{x^2 - y^2}{xy} > 0 requires numerator x2y2x^2 - y^2 and denominator xyxy to have the exact same algebraic sign.
A rational expression AB\frac{A}{B} is strictly positive if and only if A>0,B>0A > 0, B > 0 or A<0,B<0A < 0, B < 0.
2
Evaluate Case 1: Both numerator and denominator are positive (xy>0xy > 0 and x2y2>0x^2 - y^2 > 0).
xy>0    x,yxy > 0 \implies x, y have SAME signs (Opposite signs = False). x2y2>0    x>yx^2 - y^2 > 0 \implies |x| > |y| (x<y|x| < |y| = False).
The rephrased question tests 'Opposite signs     x<y\iff |x| < |y|'. Here, False     \iff False evaluates to TRUE.
3
Evaluate Case 2: Both numerator and denominator are negative (xy<0xy < 0 and x2y2<0x^2 - y^2 < 0).
xy<0    x,yxy < 0 \implies x, y have OPPOSITE signs (Opposite signs = True). x2y2<0    x<yx^2 - y^2 < 0 \implies |x| < |y| (x<y|x| < |y| = True).
The rephrased question tests 'Opposite signs     x<y\iff |x| < |y|'. Here, True     \iff True evaluates to TRUE.
4
Evaluate cases where the fraction is negative to ensure complete equivalence.
If xy>0xy > 0 and x2y2<0x^2 - y^2 < 0, we get False     \iff True (FALSE). If xy<0xy < 0 and x2y2>0x^2 - y^2 > 0, we get True     \iff False (FALSE).
The biconditional statement yields TRUE in exactly the same scenarios where x2y2xy>0\frac{x^2 - y^2}{xy} > 0, establishing strict algebraic equivalence.

Anahtar Kavram

Target Stem Rephrasing via Quotient Sign Decomposition and Logical Biconditional Equivalence
Soru 44Soru

If mm is a real number, is mm an even integer?

(1) 2m2m is an even integer.
(2) m+1m + 1 is an odd integer.

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

Cevap

Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
Statement (1) allows mm to be any integer because multiplying any integer by 22 results in an even integer. Therefore, mm could be 33 (odd) or 44 (even), making Statement (1) insufficient. Statement (2) specifies that m+1m + 1 is an odd integer. Subtracting 11 from an odd integer always yields an even integer, so mm must be an even integer. This provides a single, definitive 'Yes' answer, making Statement (2) alone sufficient.

Adım Adım Çözüm

1
Analyze the target question stem.
We need to determine whether mm is an even integer, given that mm is a real number.
Rephrasing the question clarifies that a definitive 'Yes' or definitive 'No' answer is required.
2
Evaluate Statement (1): 2m2m is an even integer.
If m=4m = 4, then 2m=82m = 8 (even integer), and mm is an even integer (Yes). If m=3m = 3, then 2m=62m = 6 (even integer), but mm is an odd integer (No).
Since Statement (1) yields both 'Yes' and 'No' answers, Statement (1) is NOT sufficient.
3
Evaluate Statement (2): m+1m + 1 is an odd integer.
If m+1m + 1 is an odd integer, then m=(m+1)1m = (m + 1) - 1. An odd integer minus 11 is always an even integer.
This guarantees that mm is an even integer, providing a definitive 'Yes'. Thus, Statement (2) ALONE is sufficient.

Anahtar Kavram

Parity and Integer Properties in Data Sufficiency
Soru 45Soru

In a GMAT Data Sufficiency 'Yes/No' question asking whether a real variable x>0x > 0, a statement that establishes definitively that x<0x < 0 is considered INSUFFICIENT because it yields a negative answer to the question stem.

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Cevap: False

Cevap

False. In a GMAT 'Yes/No' Data Sufficiency question, any statement that yields a definitive 'No' answer is sufficient.
The statement is false because GMAT Data Sufficiency decision logic defines sufficiency as achieving an unambiguous binary answer. Obtaining a conclusive 'No' settles the question entirely, rendering the statement sufficient rather than insufficient.

Adım Adım Çözüm

1
Identify the logical structure of the question stem.
The target question is a 'Yes/No' Data Sufficiency question asking whether x>0x > 0.
Understanding whether a question seeks a specific value or a binary condition determines the sufficiency rule.
2
Apply the standard GMAT Data Sufficiency rule for 'Yes/No' questions.
A statement is sufficient if and only if it leads to a consistent 'Yes' in all permissible cases or a consistent 'No' in all permissible cases.
Sufficiency means certainty of outcome, not necessarily an affirmative outcome.
3
Evaluate the outcome of a statement proving x<0x < 0.
Since x<0x < 0 guarantees that xx is never greater than 0, the answer to 'Is x>0x > 0?' is an absolute 'No'.
A guaranteed 'No' provides complete information and solves the question, making the statement sufficient.

Anahtar Kavram

Yes/No Data Sufficiency Decision Rule (Definitive No is Sufficient)
Soru 46Soru

If pp and qq are real numbers such that p0p \neq 0, is p2q<0p^2 q < 0?

(1) q5=q5|q - 5| = q - 5 and q5q \neq 5
(2) p+q=2p + q = 2

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

Cevap

Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
Rephrasing the question stem reveals that because p0p \neq 0, p2p^2 is strictly positive; thus p2q<0p^2 q < 0 is true if and only if q<0q < 0. Statement (1) dictates that q5=q5|q - 5| = q - 5 with q5q \neq 5, which implies q>5q > 5. Because qq is strictly positive, the answer to 'Is q<0q < 0?' is a definitive 'No'. In GMAT Data Sufficiency Yes/No questions, a statement that consistently yields a 'No' answer is sufficient. Statement (2) leaves qq undetermined (qq can be positive or negative depending on pp), so it is insufficient on its own.

Adım Adım Çözüm

1
Rephrase the question stem using algebraic properties.
Since pp is a non-zero real number, p2>0p^2 > 0 for all valid pp. Dividing the inequality p2q<0p^2 q < 0 by p2p^2 yields q<0q < 0. The question simplifies to: 'Is q<0q < 0?'
Simplifying the target expression reduces cognitive complexity before evaluating the statements.
2
Evaluate Statement (1) independently.
The identity k=k|k| = k holds if and only if k0k \ge 0. Thus, q5=q5    q50    q5|q - 5| = q - 5 \implies q - 5 \ge 0 \implies q \ge 5. Combined with q5q \neq 5, we obtain q>5q > 5. If q>5q > 5, then qq is strictly positive, meaning q<0q < 0 is definitively FALSE ('No'). A definitive 'No' answer is sufficient.
In Yes/No Data Sufficiency, any statement that yields a consistent 'Yes' OR a consistent 'No' is sufficient.
3
Evaluate Statement (2) independently.
Given p+q=2p + q = 2, if p=1p = 1, then q=1>0q = 1 > 0 ('No'). If p=5p = 5, then q=3<0q = -3 < 0 ('Yes'). Statement (2) allows both 'Yes' and 'No' outcomes.
Since Statement (2) cannot yield a single definitive Yes/No answer, it is not sufficient.

Anahtar Kavram

Value vs. Yes/No Data Sufficiency Decision Logic
Soru 47Soru

In GMAT Data Sufficiency logic, if a statement determines a single unique numerical value for a variable xx, that statement is sufficient to answer a 'Value' question asking for the exact value of xx, but is insufficient to answer a 'Yes/No' question asking whether x>5x > 5.

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Cevap: False

Cevap

The statement is False. A single unique value for xx provides complete information to answer both a 'Value' question for xx and any 'Yes/No' question regarding xx.
The correct response is False because a statement that yields a single unique numerical value for a variable xx provides complete information about xx. Substituting that single value into the inequality x>5x > 5 results in either a definitive 'Yes' or a definitive 'No'. Because both definitive outcomes satisfy GMAT Data Sufficiency criteria, the statement is sufficient for both question types.

Adım Adım Çözüm

1
Analyze the condition for sufficiency in a 'Value' Data Sufficiency question.
A 'Value' question requires determining one single, unique value for the variable. Finding a unique value for xx satisfies this requirement.
If more than one value is possible, the statement is insufficient.
2
Analyze the condition for sufficiency in a 'Yes/No' Data Sufficiency question.
A 'Yes/No' question requires a definitive 'Yes' or a definitive 'No'.
Sufficiency means eliminating all ambiguity in the binary decision.
3
Evaluate the effect of knowing a single unique value of xx on the inequality x>5x > 5.
If xx is fixed at a single value (e.g., x=7x = 7), the answer is a definitive 'Yes'. If xx is fixed at another single value (e.g., x=3x = 3), the answer is a definitive 'No'.
In either case, a single value produces a definitive answer with no remaining ambiguity.

Anahtar Kavram

Value vs. Yes/No Data Sufficiency Decision Logic
Soru 48Soru

If nn is a real number, is nn an integer?

(1) n23nn^2 - 3n is an integer.
(2) n2+5nn^2 + 5n is an integer.

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

Cevap

Both statements together are sufficient to answer definitively that nn is an integer, but neither statement alone is sufficient.
Neither statement alone is sufficient because quadratic equations of the form n23n=kn^2 - 3n = k and n2+5n=mn^2 + 5n = m have non-integer real roots for certain integer values of kk and mm. When both statements are combined, subtracting the two equations reveals that 8n8n is equal to an integer pp, so n=p8n = \frac{p}{8}. Substituting n=p8n = \frac{p}{8} into n23nn^2 - 3n requires p(p24)64\frac{p(p-24)}{64} to be an integer. Examining the power of 2 in p(p24)p(p-24) proves that pp must be divisible by 8, which guarantees that nn is an integer. Thus, the two statements together provide a definitive 'Yes' answer.

Adım Adım Çözüm

1
Evaluate Statement (1) independently.
Statement (1) is NOT sufficient.
If n23n=1n^2 - 3n = -1 (an integer), then n23n+1=0n^2 - 3n + 1 = 0, giving n=3+52n = \frac{3 + \sqrt{5}}{2}, which is not an integer. However, if n=3n = 3, n23n=0n^2 - 3n = 0, which is an integer. Thus, nn can be an integer or a non-integer.
2
Evaluate Statement (2) independently.
Statement (2) is NOT sufficient.
If n2+5n=1n^2 + 5n = 1 (an integer), then n2+5n1=0n^2 + 5n - 1 = 0, giving n=5+292n = \frac{-5 + \sqrt{29}}{2}, which is not an integer. However, if n=1n = 1, n2+5n=6n^2 + 5n = 6, which is an integer. Thus, nn can be an integer or a non-integer.
3
Combine Statement (1) and Statement (2).
Deduce that 8n8n must be an integer.
Let n23n=kn^2 - 3n = k and n2+5n=mn^2 + 5n = m, where kk and mm are integers. Subtracting the first equation from the second yields (n2+5n)(n23n)=mk    8n=mk(n^2 + 5n) - (n^2 - 3n) = m - k \implies 8n = m - k. Since mkm - k is an integer, let 8n=p8n = p for some integer pp. Hence, n=p8n = \frac{p}{8}.
4
Analyze whether n=p8n = \frac{p}{8} can be a non-integer fraction.
nn MUST be an integer, making BOTH statements TOGETHER sufficient.
Substitute n=p8n = \frac{p}{8} back into Statement (1): n23n=p2643p8=p224p64n^2 - 3n = \frac{p^2}{64} - \frac{3p}{8} = \frac{p^2 - 24p}{64}. For this value to be an integer, p224p=p(p24)p^2 - 24p = p(p - 24) must be divisible by 64=2664 = 2^6. If pp is odd, p24p - 24 is odd, so p(p24)p(p-24) is odd and not divisible by 64. If pp is a multiple of 2 but not 4 (p=2bp = 2b with bb odd), p(p24)=4b(b12)p(p-24) = 4b(b-12), containing only 222^2 factors of 2. If pp is a multiple of 4 but not 8 (p=4bp = 4b with bb odd), p(p24)=16b(b6)p(p-24) = 16b(b-6), containing only 242^4 factors of 2. Thus, for p(p24)p(p-24) to contain 262^6, pp must be a multiple of 8. If pp is a multiple of 8, then n=p8n = \frac{p}{8} must be an integer.

Anahtar Kavram

Evaluating integer constraints vs. real numbers in Data Sufficiency through algebraic elimination and prime factorization of rational expressions.
Soru 49Soru

For all non-zero real numbers xx and yy such that xyx \neq y, the Data Sufficiency Yes/No target question "Is xy+yx>2\frac{x}{y} + \frac{y}{x} > 2?" is algebraically equivalent to the simplified target question "Is xy>0xy > 0?"

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Cevap: True

Cevap

True
The statement is True because rewriting the inequality as (xy)2xy>0\frac{(x - y)^2}{xy} > 0 shows that since (xy)2>0(x - y)^2 > 0 for all xyx \neq y, the inequality holds if and only if xy>0xy > 0.

Adım Adım Çözüm

1
Combine the fractions on the left-hand side of the target inequality
x2+y2xy>2\frac{x^2 + y^2}{xy} > 2
Finding a common denominator xyxy combines the two reciprocal ratios into a single rational expression.
2
Move all terms to one side to compare against zero
x2+y2xy2>0    x22xy+y2xy>0\frac{x^2 + y^2}{xy} - 2 > 0 \implies \frac{x^2 - 2xy + y^2}{xy} > 0
Comparing rational expressions directly to zero simplifies testing for positive or negative regions.
3
Factor the numerator into a perfect square
(xy)2xy>0\frac{(x - y)^2}{xy} > 0
Recognizing x22xy+y2x^2 - 2xy + y^2 as (xy)2(x - y)^2 isolates a term with a guaranteed non-negative property.
4
Evaluate sign conditions under the problem constraints
Because xyx \neq y, (xy)2(x - y)^2 is strictly positive. Thus, (xy)2xy>0\frac{(x - y)^2}{xy} > 0 holds if and only if xy>0xy > 0.
A quotient with a strictly positive numerator is positive if and only if its denominator is positive.

Anahtar Kavram

Question Stem Simplification via Rational Expression Factoring
Soru 50Soru

If xx is a real number, is xx an integer?

(1) x2+xx^2 + x is an integer.
(2) x3+x2x^3 + x^2 is an integer.

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

Cevap

Both statements together are sufficient to determine that xx is an integer, but neither statement alone is sufficient.
Evaluating each statement independently reveals that non-integer real numbers can produce integer values for x2+xx^2 + x or x3+x2x^3 + x^2. However, combining both statements allows us to factor x3+x2x^3 + x^2 as x(x2+x)x(x^2 + x). Setting x2+x=mx^2 + x = m and x3+x2=kx^3 + x^2 = k for integers mm and kk, we find xm=kx \cdot m = k. If m=0m = 0, xx is 0 or -1 (integers). If m0m \neq 0, x=kmx = \frac{k}{m} is a rational number. Writing x=abx = \frac{a}{b} in lowest terms and substituting it back into x2+x=mx^2 + x = m shows that bb must divide a2a^2, forcing b=1b = 1. Thus, xx must be an integer, providing a definitive affirmative answer.

Adım Adım Çözüm

1
Evaluate Statement (1) independently.
Statement (1) is INSUFFICIENT.
If x=2x = 2, then x2+x=6x^2 + x = 6, which is an integer (YES). However, if x=1+52x = \frac{-1 + \sqrt{5}}{2}, then x2+x1=0    x2+x=1x^2 + x - 1 = 0 \implies x^2 + x = 1, which is an integer, but xx is not an integer (NO). Thus, Statement (1) alone is insufficient.
2
Evaluate Statement (2) independently.
Statement (2) is INSUFFICIENT.
If x=2x = 2, then x3+x2=12x^3 + x^2 = 12, an integer (YES). If xx is the real root of x3+x2=1x^3 + x^2 = 1 (where x0.755x \approx 0.755), x3+x2x^3 + x^2 is an integer, but xx is not an integer (NO). Thus, Statement (2) alone is insufficient.
3
Evaluate Statements (1) and (2) together.
Statements (1) and (2) together are SUFFICIENT.
Let x2+x=mx^2 + x = m where mZm \in \mathbb{Z}, and x3+x2=kx^3 + x^2 = k where kZk \in \mathbb{Z}. Notice that x3+x2=x(x2+x)=xm=kx^3 + x^2 = x(x^2 + x) = x \cdot m = k. If m=0m = 0, then x2+x=0    x=0x^2 + x = 0 \implies x = 0 or x=1x = -1, both of which are integers. If m0m \neq 0, then x=kmx = \frac{k}{m}, meaning xx must be a rational number. Express x=abx = \frac{a}{b} in lowest terms, where a,bZa, b \in \mathbb{Z}, b>0b > 0, and gcd(a,b)=1\gcd(a, b) = 1. Substituting x=abx = \frac{a}{b} into x2+x=mx^2 + x = m yields a2+abb2=m    a2+ab=mb2    a2=b(mba)\frac{a^2 + ab}{b^2} = m \implies a^2 + ab = m b^2 \implies a^2 = b(mb - a). This implies that bb must divide a2a^2. Since gcd(a,b)=1\gcd(a, b) = 1, bb can only divide a2a^2 if b=1b = 1. Therefore, x=a1=ax = \frac{a}{1} = a, which means xx MUST be an integer. The answer to the question is a definitive YES.

Anahtar Kavram

Testing real vs. integer constraints and applying rational root divisibility properties in Data Sufficiency.
Tahmini Süre:2m 0s
Soru 51Soru

If xx and yy are positive real numbers, is xx an integer?

(1) x+yx + y is an integer, and x2+xyx^2 + xy is an integer.
(2) xyx - y is an integer, and x2y2x^2 - y^2 is an integer.

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Cevap: Statements (1) and (2) TOGETHER are NOT sufficient.

Cevap

Statements (1) and (2) together are not sufficient to determine whether xx is an integer.
The correct option identifies that statements (1) and (2) together are not sufficient. Testing half-integers such as x=2.5x = 2.5 and y=1.5y = 1.5 shows that all given conditions (x+y=4x+y=4, x2+xy=10x^2+xy=10, xy=1x-y=1, x2y2=4x^2-y^2=4) are integers while xx is not an integer. Conversely, x=3x = 3 and y=1y = 1 satisfies all conditions with an integer xx. Thus, a definitive Yes/No answer cannot be determined.

Adım Adım Çözüm

1
Analyze Statement (1) independently.
Statement (1) states that x+y=kx + y = k (where kk is an integer) and x2+xy=x(x+y)=mx^2 + xy = x(x+y) = m (where mm is an integer). Thus, xk=m    x=mkx \cdot k = m \implies x = \frac{m}{k}. Since mm and kk are integers, xx is rational, but not necessarily an integer. For example, if x=1.5x = 1.5 and y=0.5y = 0.5, then x+y=2x + y = 2 (integer) and x2+xy=1.5(2)=3x^2 + xy = 1.5(2) = 3 (integer), but x=1.5x = 1.5 is not an integer. If x=2x = 2 and y=1y = 1, then x+y=3x + y = 3 and x2+xy=6x^2 + xy = 6, and x=2x = 2 is an integer. Thus, Statement (1) alone is INSUFFICIENT.
Variable xx is only constrained to be a rational number mk\frac{m}{k}, which may or may not be an integer.
2
Analyze Statement (2) independently.
Statement (2) states that xy=dx - y = d (where dd is an integer) and x2y2=(xy)(x+y)=px^2 - y^2 = (x-y)(x+y) = p (where pp is an integer). Thus d(x+y)=p    x+y=pdd(x+y) = p \implies x+y = \frac{p}{d}. Then 2x=(x+y)+(xy)=pd+d=p+d2d    x=p+d22d2x = (x+y) + (x-y) = \frac{p}{d} + d = \frac{p + d^2}{d} \implies x = \frac{p + d^2}{2d}. If x=2.5x = 2.5 and y=1.5y = 1.5, then xy=1x - y = 1 (integer) and x2y2=6.252.25=4x^2 - y^2 = 6.25 - 2.25 = 4 (integer), but x=2.5x = 2.5 is not an integer. If x=2x = 2 and y=1y = 1, xy=1x - y = 1 and x2y2=3x^2 - y^2 = 3, and x=2x = 2 is an integer. Thus, Statement (2) alone is INSUFFICIENT.
Variable xx is constrained to a rational form with denominator 2d2d, which allows non-integer values.
3
Analyze Statements (1) and (2) combined.
Combining both statements gives x+y=kx + y = k (integer) and xy=dx - y = d (integer). Adding these yields 2x=k+d2x = k + d, so 2x2x must be an integer. This means xx can be an integer or a half-integer (e.g., 2.52.5). Testing x=2.5x = 2.5 and y=1.5y = 1.5: both are positive real numbers; x+y=4x + y = 4 (integer); x2+xy=2.5(4)=10x^2 + xy = 2.5(4) = 10 (integer); xy=1x - y = 1 (integer); and x2y2=6.252.25=4x^2 - y^2 = 6.25 - 2.25 = 4 (integer). Here xx is NOT an integer. Testing x=3x = 3 and y=1y = 1: both are positive real numbers; x+y=4x + y = 4 (integer); x2+xy=3(4)=12x^2 + xy = 3(4) = 12 (integer); xy=2x - y = 2 (integer); and x2y2=91=8x^2 - y^2 = 9 - 1 = 8 (integer). Here xx IS an integer. Because both 'Yes' and 'No' answers are possible under all conditions, Statements (1) and (2) together are INSUFFICIENT.
The system of equations allows xx to be a half-integer (such as 2.52.5), satisfying all integer conditions of both statements without requiring xx itself to be an integer.

Anahtar Kavram

Evaluating implicit non-integer constraints and system degree in Data Sufficiency questions.
Soru 52Soru

If kk is a positive real number, is kk an integer?

(1) k\sqrt{k} is an integer.
(2) k24kk^2 - 4k is an integer.

Cevabı ve açıklamayı göster

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

Cevap

Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
Statement (1) alone is sufficient because if the square root of kk is an integer mm, then k=m2k = m^2, which is guaranteed to be an integer. Statement (2) alone is not sufficient because k24kk^2 - 4k can equal an integer when k=4k = 4 (an integer) or when k=2+5k = 2 + \sqrt{5} (a non-integer). Therefore, only Statement (1) is sufficient.

Adım Adım Çözüm

1
Evaluate Statement (1) independently.
If k=m\sqrt{k} = m where mm is an integer, then k=m2k = m^2. Since mm is an integer, m2m^2 must also be an integer. Thus, kk is definitely an integer (Yes).
The square of any integer is always an integer, so Statement (1) is sufficient.
2
Evaluate Statement (2) independently.
Let k24k=nk^2 - 4k = n, where nn is an integer. If n=0n = 0, then k(k4)=0    k=4k(k - 4) = 0 \implies k = 4 (an integer). If n=1n = 1, then k24k1=0    k=2+5k^2 - 4k - 1 = 0 \implies k = 2 + \sqrt{5} (not an integer).
Since kk can be either an integer or a non-integer, Statement (2) does not provide a definitive Yes/No answer and is not sufficient.

Anahtar Kavram

Algebraic definitions of integers versus real numbers in Data Sufficiency
Tahmini Süre:2m 0s
Soru 53Soru

If kk and mm are non-zero real numbers, is k>mk > m?

(1) k2>m2k^2 > m^2
(2) kmm2+1>0\frac{k - m}{m^2 + 1} > 0

Cevabı ve açıklamayı göster

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

Cevap

Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
The target question asks if k>mk > m. Evaluating Statement (1) alone: k2>m2k^2 > m^2 indicates k>m|k| > |m|, which permits cases where k>mk > m (e.g., k=3,m=2k=3, m=2) and cases where k<mk < m (e.g., k=5,m=2k=-5, m=2). Thus, Statement (1) is insufficient. Evaluating Statement (2) independently: kmm2+1>0\frac{k - m}{m^2 + 1} > 0. For any real number mm, m2+1m^2 + 1 is strictly positive. Multiplying both sides of the inequality by (m2+1)(m^2 + 1) preserves the inequality sign, yielding km>0k - m > 0, which simplifies directly to k>mk > m. This yields a definitive 'Yes' answer. Therefore, Statement (2) alone is sufficient.

Adım Adım Çözüm

1
Rephrase the target question
The target question asks whether the difference (km)(k - m) is strictly positive.
Determining if k>mk > m is algebraically equivalent to confirming km>0k - m > 0.
2
Evaluate Statement (1) independently
Statement (1) states k2>m2k^2 > m^2, which implies k>m|k| > |m|. If k=3k = 3 and m=2m = 2, then 9>49 > 4 and 3>23 > 2 (Yes). However, if k=5k = -5 and m=2m = 2, then 25>425 > 4 but 5<2-5 < 2 (No).
Because both 'Yes' and 'No' outcomes are possible, Statement (1) alone is not sufficient.
3
Evaluate Statement (2) independently without carrying over Statement (1)
Statement (2) states kmm2+1>0\frac{k - m}{m^2 + 1} > 0. Since mm is a real number, m20m^2 \ge 0, which guarantees m2+11>0m^2 + 1 \ge 1 > 0. Multiplying the inequality by the strictly positive quantity (m2+1)(m^2 + 1) preserves the inequality direction, yielding km>0k - m > 0, or k>mk > m.
This yields a definitive 'Yes' answer, so Statement (2) alone is sufficient.

Anahtar Kavram

Statement Independence in Data Sufficiency
Soru 54Soru

If pp and qq are non-zero real numbers such that pqp \neq q, is p3qpq3pq>0\frac{p^3 q - p q^3}{p - q} > 0?

(1) pq>0pq > 0
(2) p+q>0p + q > 0

Cevabı ve açıklamayı göster

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

Cevap

BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
Factoring the numerator gives p3qpq3=pq(pq)(p+q)p^3 q - p q^3 = pq(p-q)(p+q). Since pqp \neq q, dividing by (pq)(p-q) yields pq(p+q)pq(p+q). To determine whether pq(p+q)>0pq(p+q) > 0, we need the sign of the product pq(p+q)pq(p+q). Statement (1) tells us pq>0pq > 0, which is insufficient by itself because p+qp+q could be positive or negative. Statement (2) tells us p+q>0p+q > 0, which is insufficient by itself because pqpq could be positive or negative. Together, both terms pqpq and p+qp+q are positive, so their product must be positive, providing a definitive 'Yes'.

Adım Adım Çözüm

1
Rephrase the target question stem algebraically by factoring the numerator.
p3qpq3pq=pq(p2q2)pq=pq(pq)(p+q)pq=pq(p+q)\frac{p^3 q - p q^3}{p - q} = \frac{p q (p^2 - q^2)}{p - q} = \frac{p q (p - q)(p + q)}{p - q} = pq(p + q). The target question simplifies to: 'Is pq(p+q)>0pq(p+q) > 0?'
Simplifying the stem isolates the specific product whose sign determines sufficiency.
2
Evaluate Statement (1): pq>0pq > 0.
If p=1,q=1p = 1, q = 1, then pq=1>0pq = 1 > 0 and pq(p+q)=1(2)=2>0pq(p+q) = 1(2) = 2 > 0 (Yes). If p=1,q=1p = -1, q = -1, then pq=1>0pq = 1 > 0 and pq(p+q)=1(2)=2<0pq(p+q) = 1(-2) = -2 < 0 (No).
Knowing pq>0pq > 0 leaves the sign of p+qp+q unknown, so Statement (1) alone is NOT sufficient.
3
Evaluate Statement (2): p+q>0p + q > 0.
If p=2,q=1p = 2, q = 1, then p+q=3>0p+q = 3 > 0 and pq(p+q)=2(3)=6>0pq(p+q) = 2(3) = 6 > 0 (Yes). If p=3,q=1p = 3, q = -1, then p+q=2>0p+q = 2 > 0 and pq(p+q)=(3)(2)=6<0pq(p+q) = (-3)(2) = -6 < 0 (No).
Knowing p+q>0p+q > 0 leaves the sign of pqpq unknown, so Statement (2) alone is NOT sufficient.
4
Evaluate Statement (1) and Statement (2) together.
From Statement (1), pq>0pq > 0. From Statement (2), p+q>0p+q > 0. Therefore, pq(p+q)>0pq(p+q) > 0 as it is the product of two strictly positive real numbers.
Combining both statements provides a definitive 'Yes' answer to the simplified target question.

Anahtar Kavram

Question Stem Simplification and Target Rephrasing
Soru 55Soru

If aa and bb are non-zero real numbers, is a3b+ab3>0a^3 b + a b^3 > 0?

(1) a25ab+6b2=0a^2 - 5ab + 6b^2 = 0
(2) a+b<ab|a + b| < |a - b|

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

Cevabı ve açıklamayı göster

Cevap: EACH statement ALONE is sufficient.

Cevap

EACH statement ALONE is sufficient.
Rephrasing the stem shows that a3b+ab3=ab(a2+b2)>0a^3b + ab^3 = ab(a^2 + b^2) > 0 reduces to asking whether ab>0ab > 0. Statement (1) yields a=2ba = 2b or a=3ba = 3b, both of which make ab>0ab > 0 (a definitive 'Yes'). Statement (2) simplifies to 4ab<0    ab<04ab < 0 \implies ab < 0, which yields a definitive 'No'. Because each statement independently produces a definitive, consistent Yes/No answer, each statement alone is sufficient.

Adım Adım Çözüm

1
Rephrase the question stem target.
The target expression a3b+ab3a^3b + ab^3 factors into ab(a2+b2)ab(a^2 + b^2). Because aa and bb are non-zero real numbers, a2+b2>0a^2 + b^2 > 0 always. Thus, a3b+ab3>0a^3b + ab^3 > 0 if and only if ab>0ab > 0. The question reduces to a Yes/No query: 'Is ab>0ab > 0?'
Simplifying the stem isolates the essential logical condition needed to evaluate sufficiency.
2
Evaluate Statement (1) alone.
Factoring a25ab+6b2=0a^2 - 5ab + 6b^2 = 0 yields (a2b)(a3b)=0(a - 2b)(a - 3b) = 0, meaning a=2ba = 2b or a=3ba = 3b. If a=2ba = 2b, then ab=2b2>0ab = 2b^2 > 0 (since b0b \neq 0). If a=3ba = 3b, then ab=3b2>0ab = 3b^2 > 0 (since b0b \neq 0). In both cases, ab>0ab > 0 is true, giving a definitive 'Yes'.
Although Statement (1) yields two possible values for the ratio a/ba/b, both values guarantee that ab>0ab > 0. In Yes/No Data Sufficiency, a consistent 'Yes' is sufficient.
3
Evaluate Statement (2) alone.
Squaring both non-negative sides of a+b<ab|a + b| < |a - b| gives (a+b)2<(ab)2(a + b)^2 < (a - b)^2, which simplifies to a2+2ab+b2<a22ab+b2    4ab<0    ab<0a^2 + 2ab + b^2 < a^2 - 2ab + b^2 \implies 4ab < 0 \implies ab < 0. Since ab<0ab < 0, the answer to 'Is ab>0ab > 0?' is a definitive 'No'.
A statement that yields a consistent, definitive 'No' is sufficient in a Yes/No Data Sufficiency question.
4
Synthesize results.
Since Statement (1) alone produces a definitive 'Yes' and Statement (2) alone produces a definitive 'No', each statement alone is sufficient to answer the question.
Both statements independently satisfy the decision criteria for Data Sufficiency.

Anahtar Kavram

Value vs. Yes/No Data Sufficiency Decision Logic
Soru 56Soru

If aa and bb are real numbers, is a2b2>0a^2 - b^2 > 0?

(1) a<b|a| < b
(2) a+b>0a + b > 0

Cevabı ve açıklamayı göster

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

Cevap

Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
Statement (1) establishes that a<b|a| < b, which implies b>0b > 0 and a2<b2a^2 < b^2. This guarantees that a2b2<0a^2 - b^2 < 0, leading to a definitive 'No' answer to the question 'Is a2b2>0a^2 - b^2 > 0?'. In GMAT Data Sufficiency Yes/No questions, a statement that consistently leads to a 'No' answer is sufficient. Statement (2) provides a+b>0a + b > 0, which allows for cases where a2b2>0a^2 - b^2 > 0 (e.g., a=3,b=1a=3, b=1) and cases where a2b2<0a^2 - b^2 < 0 (e.g., a=1,b=3a=1, b=3), making it insufficient.

Adım Adım Çözüm

1
Analyze the target question stem
The question asks whether a2b2>0a^2 - b^2 > 0, which is equivalent to asking if a>b|a| > |b| or if a2>b2a^2 > b^2. This is a Yes/No Data Sufficiency question.
Establishing what condition constitutes a 'Yes' versus a 'No' is essential before evaluating individual statements.
2
Evaluate Statement (1): a<b|a| < b
Since a0|a| \ge 0, it follows that b>0b > 0. Squaring both non-negative sides of a<b|a| < b gives a2<b2|a|^2 < b^2, which simplifies to a2<b2a^2 < b^2. Subtracting b2b^2 yields a2b2<0a^2 - b^2 < 0.
Because a2b2<0a^2 - b^2 < 0 for all values satisfying Statement (1), the answer to 'Is a2b2>0a^2 - b^2 > 0?' is a definitive 'No'. In Data Sufficiency, a definitive 'No' means Statement (1) is ALONE sufficient.
3
Evaluate Statement (2): a+b>0a + b > 0
If a=3a = 3 and b=1b = 1, then a+b=4>0a + b = 4 > 0 and a2b2=91=8>0a^2 - b^2 = 9 - 1 = 8 > 0 (Yes). If a=1a = 1 and b=3b = 3, then a+b=4>0a + b = 4 > 0 and a2b2=19=8<0a^2 - b^2 = 1 - 9 = -8 < 0 (No).
Since Statement (2) yields both 'Yes' and 'No' responses depending on the specific values chosen, Statement (2) is NOT sufficient.
4
Determine the final Data Sufficiency decision logic
Statement (1) alone is sufficient to yield a definitive 'No' answer, while Statement (2) alone is not sufficient.
In GMAT Data Sufficiency Yes/No questions, any statement that provides a single, conclusive answer (whether 'Yes' or 'No') is sufficient.

Anahtar Kavram

Definitive No Sufficiency in Yes/No Data Sufficiency
Tahmini Süre:2m 0s
Soru 57Soru

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?

Cevabı ve açıklamayı göster

Cevap: Statement (1) ALONE is sufficient, but statement (2) alone is 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
Soru 58Soru

In a GMAT Data Sufficiency 'Yes/No' question, if a statement permits multiple numerical values for a variable, but every permitted value yields a conclusive 'No' to the question stem, the statement is sufficient to answer the question.

Cevabı ve açıklamayı göster

Cevap: True

Cevap

True
In GMAT Data Sufficiency 'Yes/No' questions, sufficiency requires a single, conclusive answer to the question asked. A statement that guarantees a 'No' answer under all valid cases is completely sufficient, even if the underlying variables can take on multiple numerical values.

Adım Adım Çözüm

1
Analyze the core rule of Yes/No Data Sufficiency questions.
A statement is sufficient if it leads to a definitive, unambiguous 'Yes' or a definitive, unambiguous 'No' answer.
Data Sufficiency evaluates whether the provided data leads to one consistent answer.
2
Evaluate the condition described in the statement.
Although multiple numerical values are possible, all permitted values consistently yield 'No'.
Because there are no scenario outcomes that yield 'Yes', there is zero ambiguity in answering the question stem.
3
Conclude sufficiency.
The statement is sufficient.
A consistent 'No' satisfies the requirement of data sufficiency just as effectively as a consistent 'Yes'.

Anahtar Kavram

Definitive Yes/No Sufficiency Rule
Soru 59Soru

If xx and yy are positive real numbers, is 1x<1y\frac{1}{x} < \frac{1}{y}?

(1) x2>y2x^2 > y^2
(2) xy>0x - y > 0

Which of the following describes the sufficiency of the statements to answer the question?

Cevabı ve açıklamayı göster

Cevap: EACH statement ALONE is sufficient.

Cevap

EACH statement ALONE is sufficient.
Rephrasing the question stem 1x<1y\frac{1}{x} < \frac{1}{y} for positive numbers xx and yy yields x>yx > y. Statement (1) states x2>y2x^2 > y^2, which for positive numbers implies x>yx > y (sufficient). Statement (2) states xy>0x - y > 0, which simplifies directly to x>yx > y (sufficient). Therefore, each statement alone is sufficient.

Adım Adım Çözüm

1
Rephrase the question stem target inequality.
Since xx and yy are both positive, multiplying 1x<1y\frac{1}{x} < \frac{1}{y} by xyxy preserves the inequality sign, yielding y<xy < x, which is equivalent to x>yx > y. The target question simplifies to: 'Is x>yx > y?'
Simplifying the target question stem allows direct evaluation of each statement.
2
Evaluate Statement (1): x2>y2x^2 > y^2.
Since xx and yy are positive real numbers, taking the positive square root of both sides of x2>y2x^2 > y^2 yields x>yx > y. This gives a definitive 'Yes' to the rephrased question.
Statement (1) alone provides sufficient information.
3
Evaluate Statement (2): xy>0x - y > 0.
Adding yy to both sides of xy>0x - y > 0 gives x>yx > y. This gives a definitive 'Yes' to the rephrased question.
Statement (2) alone provides sufficient information.

Anahtar Kavram

Question Stem Simplification and Target Rephrasing
Soru 60Soru

If xx and yy are real numbers, is x>yx > y?

(1) yx=x+3+1y - x = |x + 3| + 1
(2) x+y=10x + y = 10

Cevabı ve açıklamayı göster

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

Cevap

Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
The option stating that Statement (1) alone is sufficient while Statement (2) alone is not is correct. Statement (1) demonstrates that yx=x+3+11y - x = |x + 3| + 1 \ge 1, which proves y>xy > x. Consequently, the answer to 'Is x>yx > y?' is a guaranteed, definitive 'No'. In GMAT Yes/No Data Sufficiency questions, any statement that yields a conclusive 'No' is sufficient. Statement (2) allows multiple relative orderings of xx and yy, making it insufficient.

Adım Adım Çözüm

1
Analyze the question stem
The target is a Yes/No question: 'Is x>yx > y?' Any statement that yields a definitive 'Yes' OR a definitive 'No' is sufficient.
Data Sufficiency Yes/No decision logic requires evaluating whether a statement yields a single consistent truth value.
2
Evaluate Statement (1): yx=x+3+1y - x = |x + 3| + 1
Since absolute value is always non-negative (x+30|x + 3| \ge 0), we have yx0+1=1>0y - x \ge 0 + 1 = 1 > 0. Thus, yx>0    y>xy - x > 0 \implies y > x.
Because y>xy > x is always true under Statement (1), the answer to 'Is x>yx > y?' is a definitive 'No'.
3
Conclude sufficiency for Statement (1)
A definitive 'No' is SUFFICIENT. Statement (1) alone is sufficient.
In GMAT Data Sufficiency, a consistent negative answer resolves the question completely.
4
Evaluate Statement (2): x+y=10x + y = 10
If x=6x = 6 and y=4y = 4, then x>yx > y is 'Yes'. If x=4x = 4 and y=6y = 6, then x>yx > y is 'No'.
Since both 'Yes' and 'No' are possible, Statement (2) alone is NOT sufficient.

Anahtar Kavram

Definitive Yes/No Decision Logic in Data Sufficiency
ÖncekiSayfa 3 / 14Sonraki
Data Sufficiency Alıştırma Soruları — GMAT — Sayfa 3 | Examkin