Researchers studying long-term changes in regional mouse populations have found that by focusing on the populations of a rare but...

GMAT Multi Source Reasoning : (MSR) Questions

Source: Mock

Multi Source Reasoning

Case Study

HARD

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Research Study

Data Tables

Researchers studying long-term changes in regional mouse populations have found that by focusing on the populations of a rare but widespread and easily identifiable species of mouse (Species X), they can make fairly accurate estimations about the total regional mouse populations.

In a report on a recent study that included the data tables that follow, the researchers provided some addenda:

The Species X population of Region CV increased by 123,995 between 1990 and 2005.
In contrast, the Species X population of Region EW declined by about 52% during that same time.

Ques. 1/3

For each of the following statements, select Yes if the statement is accurate based on the information in the passage and tables. Otherwise, select No.

Yes

The total mouse population of TY changed more from 1960 to 1975 than from 1975 to 1990.

Yes

Rounded to the nearest million, the total mouse population of TY was 47 million in 1990.

Yes

The total mouse population of TY fell from 1975 to 1990.

Solution

Owning the Dataset

Understanding Source A: Text Source - Research Study

Information from Dataset	Analysis
""Researchers studying long-term changes in regional mouse populations have found that by focusing on the populations of a rare but widespread and easily identifiable species of mouse (Species X), they can make fairly accurate estimations about the total regional mouse populations.""	Species X serves as an indicator species for tracking overall mouse populations Three key characteristics: rare, widespread, and easily identifiable Relationship consistency: The connection between Species X and total populations allows ""fairly accurate"" estimates
""The Species X population of Region CV increased by 123,995 between 1990 and 2005.""	CV region experienced significant growth in Species X Precise tracking methods suggested by the specific number (123,995) Timeframe: 15-year measurement period (1990-2005)
""In contrast, the Species X population of Region EW declined by about 52% during that same time.""	EW region experienced major population decline Approximation: Use of ""about"" suggests estimate rather than exact figure Opposite trends: CV and EW regions had contrasting population patterns

Summary: Research study establishes Species X as a reliable indicator for total mouse populations, with specific examples showing CV region growth and EW region decline between 1990-2005

Understanding Source B: Data Tables - Species X Population Data

Table Contents:
- Two tables presenting Species X population data across six regions (CV, EW, IQ, JR, PS, TY)
- Three time periods covered: 1960, 1975, 1990
- First table: Absolute population numbers
- Second table: Species X as percentage of total mouse population
Key Patterns:
- Species X populations range from 20,760 (JR, 1990) to 1,859,460 (IQ, 1960)
- IQ region: Dramatic continuous decline: 1,859,460 → 928,340 → 465,610
- EW region: Stability then growth: 393,260 → 392,080 → 964,020
- Most regions show declining percentages over time
Species Rarity Confirmed: Never exceeds 4% of total mouse population (highest: TY at 3.356% in 1960)
EW Growth Pattern: Only region showing significant growth by 1990, more than doubling between 1975-1990
Continuous Coverage: Source B data ends in 1990, exactly where Source A's timeframe begins (1990-2005), providing 45-year coverage
Regional Population Peaks: EW shows opposite trends - growth through 1990 in Source B, then 52% decline after 1990 in Source A

Summary: Historical data reveals highly variable Species X populations across regions, with most experiencing declines except EW which grew dramatically before 1990, confirming Species X's rarity and validating its use as an indicator species

Overall Summary

Data Coverage: Nearly half a century of continuous Species X population data (1960-2005)
Rarity Confirmation: Species X consistently represents less than 4% of total mouse populations
EW Population Peak: Around 1990 - growing dramatically before then declining sharply after
Accuracy Level: Percentage variation (0.255% to 3.356%) explains why estimates are ""fairly accurate"" rather than precise
Methodology Validation: Sources together validate using this rare species to estimate total mouse populations across regions

Question Analysis

Task: Evaluate three statements about the total mouse population of the TY region across different time periods
Requirements:
- Must evaluate each statement as Yes or No
- Focus specifically on TY region
- Statements concern TOTAL mouse population, not just Species X
- Need to calculate total populations from Species X data and percentages
Answer Type: Numerical calculation and verification of claims about population changes

Connecting to Our Passage Analysis

Calculation Required: The analysis doesn't directly address total mouse populations for TY region - must calculate from Species X population and percentage data in Source B tables
Formula: Total Population = Species X Population ÷ (Percentage ÷ 100)
Source: Cannot answer from analysis alone - requires calculation using Source B data

Extracting Relevant Findings

TY Region Data from Source B:
- Species X populations: 1960: 947,630; 1975: 144,520; 1990: 968,460
- Percentages: 1960: 3.356%; 1975: 0.351%; 1990: 2.051%

Statement 1 Evaluation

Question: Did TY's total mouse population change more between 1960-1975 than between 1975-1990?
Calculations:
- 1960 total: 947,630 ÷ 0.03356 = 28,236,423
- 1975 total: 144,520 ÷ 0.00351 = 41,188,034
- 1990 total: 968,460 ÷ 0.02051 = 47,219,893
Change 1960-1975: From 28,236,423 to 41,188,034 = increase of 12,951,611
Change 1975-1990: From 41,188,034 to 47,219,893 = increase of 6,031,859
Result: 12,951,611 > 6,031,859
YES - The population changed more (~13 million increase) from 1960-1975 than from 1975-1990 (~6 million increase)

Statement 2 Evaluation

Question: Was TY's total mouse population 47 million in 1990 when rounded to the nearest million?
1990 total population: 968,460 ÷ 0.02051 = 47,219,893
Rounded to nearest million: 47,000,000
YES - The 1990 population of 47,219,893 rounds to 47 million

Statement 3 Evaluation

Question: Did TY's total mouse population decrease from 1975 to 1990?
1975 population: 41,188,034
1990 population: 47,219,893
Comparison: 47,219,893 > 41,188,034 (increased, not decreased)
NO - The population INCREASED from 41.2 million to 47.2 million, not fell

Calculation Verification

Formula Check: Species X population divided by percentage as decimal
- 1960: 947,630 ÷ 0.03356 = 28,236,423
- 1975: 144,520 ÷ 0.00351 = 41,188,034
- 1990: 968,460 ÷ 0.02051 = 47,219,893
All three statements evaluated using calculated totals

Final Answer: Yes, Yes, No

Answer Choices Explained

Yes

The total mouse population of TY changed more from 1960 to 1975 than from 1975 to 1990.

Yes

Rounded to the nearest million, the total mouse population of TY was 47 million in 1990.

Yes

The total mouse population of TY fell from 1975 to 1990.

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