Overlapping Sets, Statistics, and Data Distributions

27 questions

Question 21Question

In a financial firm, a total of 100100 portfolio audits were conducted last year. Each audit was classified as High-Risk, International, or both. Exactly 6060 audits were classified as High-Risk, and exactly 5050 audits were classified as International. What was the average (arithmetic mean) duration, in days, of the 100100 portfolio audits?

(1) The average duration of the High-Risk audits was 1414 days, and the average duration of the International audits was 1818 days.
(2) The average duration of the audits classified as both High-Risk and International was 2020 days.

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.
The correct answer states that both statements together are sufficient, but neither statement alone is sufficient. By set theory, the number of audits in both categories is 60+50100=1060 + 50 - 100 = 10. The total sum of days across all 100100 audits satisfies Stotal=SHigh-Risk+SInternationalSBothS_{\text{total}} = S_{\text{High-Risk}} + S_{\text{International}} - S_{\text{Both}}. Statement (1) gives SHigh-Risk=60×14=840S_{\text{High-Risk}} = 60 \times 14 = 840 and SInternational=50×18=900S_{\text{International}} = 50 \times 18 = 900, yielding Stotal=1740SBothS_{\text{total}} = 1740 - S_{\text{Both}}, which is insufficient alone. Statement (2) gives SBoth=10×20=200S_{\text{Both}} = 10 \times 20 = 200, which is insufficient alone. Combining both gives Stotal=1740200=1540S_{\text{total}} = 1740 - 200 = 1540 days, allowing us to find a unique overall mean of 15.415.4 days.

Step-by-Step Solution

1
Determine set sizes using Principle of Inclusion-Exclusion.
Total N=100N = 100. N(H)=60N(H) = 60, N(I)=50N(I) = 50. Since every audit is in HH, II, or both, N(HI)=100=60+50N(HI)    N(HI)=10N(H \cup I) = 100 = 60 + 50 - N(H \cap I) \implies N(H \cap I) = 10.
Identify the count of audits in the overlapping set (both High-Risk and International).
2
Formulate total duration sum in terms of set sums.
Stotal=SH+SISHIS_{\text{total}} = S_H + S_I - S_{H \cap I}, where SHS_H is sum of High-Risk durations, SIS_I is sum of International durations, and SHIS_{H \cap I} is sum of durations in both categories.
Double counting principle applies to the sum of values across sets.
3
Evaluate Statement (1) alone.
SH=60×14=840S_H = 60 \times 14 = 840 days, SI=50×18=900S_I = 50 \times 18 = 900 days. Stotal=840+900SHI=1740SHIS_{\text{total}} = 840 + 900 - S_{H \cap I} = 1740 - S_{H \cap I}.
Since SHIS_{H \cap I} is unknown, StotalS_{\text{total}} cannot be calculated. Statement (1) alone is insufficient.
4
Evaluate Statement (2) alone.
SHI=10×20=200S_{H \cap I} = 10 \times 20 = 200 days.
Without SHS_H or SIS_I, StotalS_{\text{total}} cannot be calculated. Statement (2) alone is insufficient.
5
Evaluate Statements (1) and (2) together.
Stotal=1740200=1540S_{\text{total}} = 1740 - 200 = 1540 days. Mean duration = 1540/100=15.41540 / 100 = 15.4 days.
A unique value for the overall mean is obtained. Both statements together are sufficient.

Key Concept

Overlapping Sets and Weighted Averages (Sum Double Counting)
Estimated Time:2m 0s
Question 22Question

A financial advisory firm manages a portfolio of 9090 assets, each of which is classified as a Tech asset, a Biotech asset, or both. Exactly 5050 of the assets are Tech assets, and exactly 6060 of the assets are Biotech assets. Is the average (arithmetic mean) value of the Tech-only assets greater than the average value of the Biotech-only assets?

(1) The average value of all 5050 Tech assets is $12\$12 million, and the average value of all 6060 Biotech assets is $12\$12 million.
(2) The average value of the 2020 assets classified as both Tech and Biotech assets is $15\$15 million.

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.
Combining both statements allows us to solve for the exact average value of the Tech-only assets (1010 million) and the Biotech-only assets (10.510.5 million). Because we can answer the stem's question with a definitive 'No' (1010 is not greater than 10.510.5), both statements together are sufficient.

Step-by-Step Solution

1
Determine the number of assets in each non-overlapping subgroup using set theory.
Total assets N=90N = 90, Tech assets T=50|T| = 50, Biotech assets B=60|B| = 60. Using TB=T+BTB|T \cup B| = |T| + |B| - |T \cap B|, we get 90=50+60TB    TB=2090 = 50 + 60 - |T \cap B| \implies |T \cap B| = 20. Therefore, Tech-only assets =5020=30= 50 - 20 = 30, Biotech-only assets =6020=40= 60 - 20 = 40, and Both =20= 20.
Rephrasing the question stem into distinct, non-overlapping subset counts simplifies the algebraic system.
2
Evaluate Statement (1) independently.
Let MTM_{T}, MBM_{B}, and MbothM_{both} represent the mean values of Tech-only, Biotech-only, and Both subsets respectively. From Statement (1), total value of Tech =30MT+20Mboth=50×12=600= 30 M_T + 20 M_{both} = 50 \times 12 = 600, and total value of Biotech =40MB+20Mboth=60×12=720= 40 M_B + 20 M_{both} = 60 \times 12 = 720. Subtracting the equations yields 40MB30MT=120    4MB3MT=1240 M_B - 30 M_T = 120 \implies 4 M_B - 3 M_T = 12.
Since MTM_T could be 1616 (making MB=15M_B = 15, so MT>MBM_T > M_B is Yes) or MTM_T could be 88 (making MB=9M_B = 9, so MT>MBM_T > M_B is No), Statement (1) alone is NOT sufficient.
3
Evaluate Statement (2) independently.
Statement (2) gives Mboth=15M_{both} = 15. Without knowing the total asset values or subgroup means, we cannot compare MTM_T and MBM_B.
Statement (2) alone is NOT sufficient.
4
Evaluate Statements (1) and (2) together.
Substituting Mboth=15M_{both} = 15 into Statement (1) equations: 30MT+20(15)=600    30MT=300    MT=1030 M_T + 20(15) = 600 \implies 30 M_T = 300 \implies M_T = 10. Similarly, 40MB+20(15)=720    40MB=420    MB=10.540 M_B + 20(15) = 720 \implies 40 M_B = 420 \implies M_B = 10.5. Since 10>10.510 > 10.5 is definitively FALSE, we get a clear 'No' response.
In Yes/No Data Sufficiency questions, a definitive 'No' means the combined statements are sufficient.

Key Concept

Data Sufficiency decision logic for overlapping sets combined with weighted averages
Estimated Time:2m 0s
Question 23Question

In a commercial survey of 120120 retail stores, each store sells products from Brand P, Brand Q, or both. The average (arithmetic mean) monthly revenue of the stores that sell Brand P is $40,000\$40,000, and the average monthly revenue of the stores that sell Brand Q is $50,000\$50,000. What is the average monthly revenue of all 120120 stores combined?

(1) Exactly 3030 stores sell both Brand P and Brand Q, and their average monthly revenue is $60,000\$60,000.
(2) Exactly 4040 stores sell only Brand P.

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.
The correct response identifies that neither statement alone provides enough information to determine both the exact store counts in each category and the overlap revenue sum, but combining both statements gives a unique system of linear equations that yields an exact combined average revenue of $5,000,000120$41,666.67\frac{\$5,000,000}{120} \approx \$41,666.67.

Step-by-Step Solution

1
Formulate the total revenue expression in terms of overlapping sets and subgroup means.
Let n(P)n(P) be the number of stores selling Brand P and n(Q)n(Q) be the number of stores selling Brand Q. Total stores N=n(P only)+n(Q only)+n(PQ)=120N = n(P \text{ only}) + n(Q \text{ only}) + n(P \cap Q) = 120. Total revenue Stotal=S(P)+S(Q)S(PQ)=40,000n(P)+50,000n(Q)S(PQ)S_{total} = S(P) + S(Q) - S(P \cap Q) = 40,000 n(P) + 50,000 n(Q) - S(P \cap Q).
Stores selling both brands are counted twice when summing S(P)S(P) and S(Q)S(Q), so their revenue sum S(PQ)S(P \cap Q) must be subtracted once.
2
Evaluate Statement (1) alone.
Statement (1) gives n(PQ)=30n(P \cap Q) = 30 and average overlap revenue =$60,000    S(PQ)=30×60,000=1,800,000= \$60,000 \implies S(P \cap Q) = 30 \times 60,000 = 1,800,000. Also n(P)+n(Q)=120+30=150n(P) + n(Q) = 120 + 30 = 150.
Since n(P)n(P) and n(Q)n(Q) can still vary while their sum is 150150 (e.g., n(P)=70,n(Q)=80n(P)=70, n(Q)=80 vs n(P)=90,n(Q)=60n(P)=90, n(Q)=60), Stotal=40,000n(P)+50,000n(Q)1,800,000S_{total} = 40,000 n(P) + 50,000 n(Q) - 1,800,000 yields multiple possible total values. Statement (1) alone is INSUFFICIENT.
3
Evaluate Statement (2) alone.
Statement (2) gives n(P only)=40n(P \text{ only}) = 40. Thus n(Q)=12040=80n(Q) = 120 - 40 = 80.
No revenue information or overlap count is given. Statement (2) alone is INSUFFICIENT.
4
Evaluate Statements (1) and (2) together.
From Statement (2), n(P only)=40n(P \text{ only}) = 40. From Statement (1), n(PQ)=30n(P \cap Q) = 30. Thus n(P)=40+30=70n(P) = 40 + 30 = 70. Since n(P)+n(Q)=150n(P) + n(Q) = 150, n(Q)=80n(Q) = 80.
We now have exact values: n(P)=70n(P) = 70, n(Q)=80n(Q) = 80, S(PQ)=1,800,000S(P \cap Q) = 1,800,000. Stotal=40,000(70)+50,000(80)1,800,000=2,800,000+4,000,0001,800,000=5,000,000S_{total} = 40,000(70) + 50,000(80) - 1,800,000 = 2,800,000 + 4,000,000 - 1,800,000 = 5,000,000. Combined mean revenue =5,000,000120=$41,666.67= \frac{5,000,000}{120} = \$41,666.67. Both statements together are SUFFICIENT.

Key Concept

Weighted averages in overlapping sets requiring exact subgroup counts and sum reconciliations.
Question 24Question

In a laboratory, 8080 experimental trials were conducted. Each trial was monitored by Sensor P, Sensor Q, or both. The average (arithmetic mean) duration of the trials monitored by Sensor P only was 4545 minutes, and the average duration of the trials monitored by Sensor Q only was 6060 minutes. What was the average duration of all 8080 trials?

(1) Exactly 2020 trials were monitored by Sensor P only, and 3030 trials were monitored by Sensor Q only.
(2) The average duration of all trials monitored by Sensor Q was 5555 minutes, and the average duration of the trials monitored by both sensors was 5050 minutes.

Show answer & explanation

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

Answer

Both statements together are sufficient to answer the question, but neither statement alone is sufficient.
Evaluating Statement (1) gives the counts for all three disjoint regions (2020 P-only, 3030 Q-only, and 3030 Both), but does not provide the mean duration of the 3030 trials in the 'Both' category. Evaluating Statement (2) gives the mean duration of the 'Both' category (5050 minutes) and establishes that nB=nQn_{B} = n_{Q}, but does not give absolute counts. Combining both statements provides all subgroup sizes and their respective means, allowing us to calculate the exact weighted average of 52.552.5 minutes.

Step-by-Step Solution

1
Formulate the algebraic expressions for total trials and total duration.
Let nPn_{P}, nQn_{Q}, and nBn_{B} be the counts for Sensor P only, Sensor Q only, and Both sensors respectively. nP+nQ+nB=80n_{P} + n_{Q} + n_{B} = 80. The total duration is 45nP+60nQ+MBnB45 n_{P} + 60 n_{Q} + M_{B} n_{B}, where MBM_{B} is the mean duration of the trials monitored by both sensors.
Deconstruct the overlapping sets into three mutually exclusive subgroups: P only, Q only, and Both.
2
Evaluate Statement (1) alone.
nP=20n_{P} = 20 and nQ=30    nB=802030=30n_{Q} = 30 \implies n_{B} = 80 - 20 - 30 = 30. Total duration =45(20)+60(30)+MB(30)=2700+30MB= 45(20) + 60(30) + M_{B}(30) = 2700 + 30 M_{B}.
Since the mean duration MBM_{B} for trials monitored by both sensors is unknown, Statement (1) is insufficient.
3
Evaluate Statement (2) alone.
The total group Q consists of Q only (nQn_{Q}, mean 6060) and Both (nBn_{B}, mean 5050). Average for Q is 55    60nQ+50nBnQ+nB=55    5nB=5nQ    nB=nQ55 \implies \frac{60 n_{Q} + 50 n_{B}}{n_{Q} + n_{B}} = 55 \implies 5 n_{B} = 5 n_{Q} \implies n_{B} = n_{Q}.
Statement (2) proves nB=nQn_{B} = n_{Q}, which gives nP+2nQ=80n_{P} + 2 n_{Q} = 80, but without specific numbers for nQn_{Q} or nPn_{P}, the overall average cannot be uniquely determined. Thus Statement (2) is insufficient.
4
Evaluate Statements (1) and (2) together.
From (1), nP=20n_{P} = 20 and nQ=30n_{Q} = 30, so nB=30n_{B} = 30. From (2), MB=50M_{B} = 50. Total duration =45(20)+60(30)+50(30)=900+1800+1500=4200= 45(20) + 60(30) + 50(30) = 900 + 1800 + 1500 = 4200. Overall average =420080=52.5= \frac{4200}{80} = 52.5 minutes.
Combining both statements yields a unique numeric value for the overall average duration.

Key Concept

Weighted Averages and Overlapping Sets Partitioning
Question 25Question

A summer academic camp has a total of 120120 enrolled students. Every student participates in at least one of two workshops: Data Analysis or Public Speaking. Exactly 7070 students participate in Data Analysis and exactly 8080 students participate in Public Speaking. What is the average (arithmetic mean) test score of the students who participate ONLY in Public Speaking?

Statement (1): The average test score of all 120120 students in the camp is 8484.
Statement (2): The average test score of the students who participate in BOTH workshops is 9090, and the average test score of the students who participate ONLY in Data Analysis is 7878.

Show answer & explanation

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

Answer

Both statements together are sufficient to uniquely determine the average score of the students participating only in Public Speaking, but neither statement alone is sufficient.
The correct response identifies that both statements together provide enough information to solve for the target average, whereas neither statement alone is sufficient. By deconstructing the overlapping sets into three distinct groups (Data Analysis only = 40, Both = 30, Public Speaking only = 50), the weighted average equation connects the overall average to the three subgroup averages. Statement (1) supplies only the overall average, leaving two unknown subgroup averages. Statement (2) supplies two subgroup averages, leaving the overall average unknown. Combining both statements yields a single equation with only one unknown (AP-only=85.2A_{P\text{-only}} = 85.2), producing a unique numerical solution.

Step-by-Step Solution

1
Rephrase the question stem by calculating the exact number of students in each mutually exclusive subset.
Using the overlapping sets formula N(DP)=N(D)+N(P)N(DP)N(D \cup P) = N(D) + N(P) - N(D \cap P), we get 120=70+80N(DP)120 = 70 + 80 - N(D \cap P), so N(DP)=30N(D \cap P) = 30 students in both workshops. Therefore, students in Data Analysis only = 7030=4070 - 30 = 40, students in Public Speaking only = 8030=5080 - 30 = 50, and students in both = 3030.
Deconstructing the overlapping sets into three distinct, non-overlapping groups (Data Analysis only, Both, Public Speaking only) is essential for formulating a weighted average equation.
2
Formulate the weighted average equation relating all subset averages to the total average.
Total Score Sum = 120Atotal=40AD-only+30Aboth+50AP-only120 \cdot A_{total} = 40 \cdot A_{D\text{-only}} + 30 \cdot A_{both} + 50 \cdot A_{P\text{-only}}, where AP-onlyA_{P\text{-only}} is the target value.
The total sum of all scores is the weighted sum of scores from the three mutually exclusive subsets.
3
Evaluate Statement (1) independently.
Statement (1) gives Atotal=84A_{total} = 84. Substituting gives 120(84)=10080=40AD-only+30Aboth+50AP-only120(84) = 10080 = 40 \cdot A_{D\text{-only}} + 30 \cdot A_{both} + 50 \cdot A_{P\text{-only}}. Since AD-onlyA_{D\text{-only}} and AbothA_{both} remain unknown, AP-onlyA_{P\text{-only}} cannot be uniquely solved.
One linear equation with three unknown variables does not yield a unique solution. Statement (1) alone is NOT sufficient.
4
Evaluate Statement (2) independently.
Statement (2) gives Aboth=90A_{both} = 90 and AD-only=78A_{D\text{-only}} = 78. Substituting gives 120Atotal=40(78)+30(90)+50AP-only=5820+50AP-only120 \cdot A_{total} = 40(78) + 30(90) + 50 \cdot A_{P\text{-only}} = 5820 + 50 \cdot A_{P\text{-only}}. Since AtotalA_{total} is unknown, AP-onlyA_{P\text{-only}} cannot be uniquely solved.
One linear equation with two unknown variables does not yield a unique solution. Statement (2) alone is NOT sufficient.
5
Evaluate Statement (1) and Statement (2) combined.
Combining both statements provides Atotal=84A_{total} = 84, Aboth=90A_{both} = 90, and AD-only=78A_{D\text{-only}} = 78. The equation becomes 120(84)=40(78)+30(90)+50AP-only120(84) = 40(78) + 30(90) + 50 \cdot A_{P\text{-only}}, which simplifies to 10080=5820+50AP-only    4260=50AP-only    AP-only=85.210080 = 5820 + 50 \cdot A_{P\text{-only}} \implies 4260 = 50 \cdot A_{P\text{-only}} \implies A_{P\text{-only}} = 85.2.
We have one linear equation with only one unknown variable, giving a single unique numerical value. Both statements together are SUFFICIENT.

Key Concept

Combining overlapping set cardinalities with group weighted averages in Data Sufficiency
Estimated Time:2m 0s
Question 26Question

A medical research trial evaluated 100100 patients, each of whom experienced side effect A, side effect B, or both. Exactly 6565 patients experienced side effect A, and exactly 5555 patients experienced side effect B. What was the average (arithmetic mean) duration of side effect A, in days, among all patients who experienced side effect A?

(1) The average duration of side effect A for patients who experienced ONLY side effect A was 88 days.
(2) The average duration of side effect A for patients who experienced BOTH side effects was 1212 days.

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.
The correct choice indicates that both statements combined provide sufficient data while neither is sufficient on its own. Using the standard inclusion-exclusion principle for two sets, 100=65+55N(Both)100 = 65 + 55 - N(\text{Both}), giving exactly 2020 patients with both side effects and 4545 patients with only side effect A. Statement (1) provides the sum of durations for the 4545 patients (45×8=36045 \times 8 = 360), and Statement (2) provides the sum of durations for the 2020 patients (20×12=24020 \times 12 = 240). Neither statement alone gives both sums, but together they yield a total sum of 600600 days for 6565 patients, resulting in a single definitive mean of 60065\frac{600}{65} days.

Step-by-Step Solution

1
Rephrase the question stem using overlapping sets principles.
Let N(A)=65N(A) = 65, N(B)=55N(B) = 55, and total patients N(AB)=100N(A \cup B) = 100. Using the set formula N(AB)=N(A)+N(B)N(AB)N(A \cup B) = N(A) + N(B) - N(A \cap B), we get 100=65+55N(AB)100 = 65 + 55 - N(A \cap B), so N(AB)=20N(A \cap B) = 20.
Determining the exact count of patients in the overlap region (ABA \cap B) and the exclusive region (A onlyA \text{ only}) is necessary to set up the weighted average formula.
2
Calculate the subgroup sizes for patients experiencing side effect A.
Patients with ONLY side effect A = N(A)N(AB)=6520=45N(A) - N(A \cap B) = 65 - 20 = 45. Patients with BOTH side effects = 2020. Total patients with side effect A = 6565.
The total duration of side effect A across all 6565 patients is the sum of durations from the 4545 'only A' patients and the 2020 'both' patients.
3
Evaluate Statement (1) independently.
Statement (1) states that the mean for the 4545 'only A' patients is 88 days. The total duration for this group is 45×8=36045 \times 8 = 360 days. However, the duration for the 2020 'both' patients is unknown.
Without the total duration for the overlap group, the overall mean cannot be determined. Thus, Statement (1) alone is NOT sufficient.
4
Evaluate Statement (2) independently.
Statement (2) states that the mean for the 2020 'both' patients is 1212 days. The total duration for this group is 20×12=24020 \times 12 = 240 days. However, the duration for the 4545 'only A' patients is unknown.
Without the total duration for the exclusive A group, the overall mean cannot be determined. Thus, Statement (2) alone is NOT sufficient.
5
Evaluate Statement (1) and Statement (2) together.
Combining both statements, the total duration for all 6565 patients with side effect A is 360+240=600360 + 240 = 600 days. The overall average duration is 60065=12013\frac{600}{65} = \frac{120}{13} days.
A unique numerical value is obtained for the target question, so both statements together are sufficient.

Key Concept

Combining overlapping set subgroup sizes with weighted arithmetic mean formulas to evaluate Data Sufficiency statements.
Estimated Time:2m 0s
Question 27Question

A dataset consists of 1515 distinct positive integers. Is the median of the dataset greater than its arithmetic mean?

(1) The sum of the 77 smallest integers in the dataset is 4242, and the sum of the 77 largest integers in the dataset is 140140.
(2) The dataset forms an arithmetic progression.

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 option stating that Statement (2) alone is sufficient while Statement (1) alone is not sufficient is correct because Statement (2) establishes that the dataset is an arithmetic progression, where median always equals mean. This provides a definitive 'No' to the question of whether the median is strictly greater than the mean, satisfying sufficiency. Statement (1) allows values of the median both above and below 1313, yielding both 'Yes' and 'No' outcomes.

Step-by-Step Solution

1
Rephrase the question stem mathematically.
Let the 15 distinct positive integers be ordered as x1<x2<<x7<x8<x9<<x15x_1 < x_2 < \dots < x_7 < x_8 < x_9 < \dots < x_{15}. The median is x8x_8, and the arithmetic mean is μ=i=115xi15\mu = \frac{\sum_{i=1}^{15} x_i}{15}. We need to determine whether x8>μx_8 > \mu.
Simplifying the question target clarifies what information is necessary for sufficiency.
2
Evaluate Statement (1) independently.
Statement (1) gives i=17xi=42\sum_{i=1}^7 x_i = 42 and i=915xi=140\sum_{i=9}^{15} x_i = 140. The total sum is 42+x8+140=182+x842 + x_8 + 140 = 182 + x_8, so the mean is μ=182+x815\mu = \frac{182 + x_8}{15}. The inequality x8>182+x815x_8 > \frac{182 + x_8}{15} simplifies to 14x8>18214 x_8 > 182, or x8>13x_8 > 13. If x8=10x_8 = 10 (with x1x7={3,4,5,6,7,8,9}x_1 \dots x_7 = \{3,4,5,6,7,8,9\} and x9x15={11,12,13,14,15,16,59}x_9 \dots x_{15} = \{11,12,13,14,15,16,59\}), then x813x_8 \le 13 yields 'No'. If x8=15x_8 = 15 (with x1x7={1,2,3,4,5,13,14}x_1 \dots x_7 = \{1,2,3,4,5,13,14\} and x9x15={16,17,18,19,20,21,29}x_9 \dots x_{15} = \{16,17,18,19,20,21,29\}), then x8>13x_8 > 13 yields 'Yes'.
Since Statement (1) allows for both 'Yes' and 'No' answers, it is NOT sufficient.
3
Evaluate Statement (2) independently.
Statement (2) states that the elements form an arithmetic progression. In any set of numbers that forms an arithmetic progression, the distribution is perfectly symmetric, so the arithmetic mean is exactly equal to the median (x8=μx_8 = \mu). Therefore, x8>μx_8 > \mu is false, giving a definitive answer of 'No'.
In Data Sufficiency Yes/No questions, a definitive 'No' answer establishes that the statement IS sufficient.

Key Concept

Data Sufficiency evaluation of data distributions, comparing median and arithmetic mean in symmetric versus asymmetric datasets.
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