An environmental scientist is evaluating air quality measurements from monitoring stations across a metropolitan area. The following readings show par...
GMAT Information and Ideas : (Ideas) Questions
An environmental scientist is evaluating air quality measurements from monitoring stations across a metropolitan area. The following readings show particulate matter concentrations (PM2.5) in micrograms per cubic meter:
- Downtown Station: \(18.7\text{ μg/m³}\)
- Suburban Station: \(12.3\text{ μg/m³}\)
- Industrial Station: \(24.1\text{ μg/m³}\)
- Residential Station: \(14.6\text{ μg/m³}\)
- Waterfront Station: \(16.2\text{ μg/m³}\)
The scientist notes that according to environmental standards, readings above \(15.0\text{ μg/m³}\) indicate moderate air pollution levels. Based on this threshold, the scientist determines that ______
Which choice most effectively uses data from the readings to complete the statement?
Only the Industrial Station recorded readings that significantly exceed the moderate pollution threshold.
The Suburban Station and Residential Station both recorded readings above the moderate pollution threshold.
Three of the five monitoring stations recorded readings above the moderate pollution threshold.
All monitoring stations except the Downtown Station recorded readings below the moderate pollution threshold.
Step 1: Decode and Map the Passage
Part A: Passage Analysis Table
| Text from Passage | Analysis |
|---|---|
| 'An environmental scientist is evaluating air quality measurements from monitoring stations across a metropolitan area.' |
|
| 'The following readings show particulate matter concentrations (PM2.5) in micrograms per cubic meter:' |
|
| 'Downtown Station: 18.7 μg/m³, Suburban Station: 12.3 μg/m³, Industrial Station: 24.1 μg/m³, Residential Station: 14.6 μg/m³, Waterfront Station: 16.2 μg/m³' |
|
| 'The scientist notes that according to environmental standards, readings above 15.0 μg/m³ indicate moderate air pollution levels.' |
|
| 'Based on this threshold, the scientist determines that ______' |
|
Part B: Passage Architecture & Core Elements
Main Point: A scientist is analyzing air quality data from five monitoring stations and needs to draw a conclusion based on how many exceed the 15.0 μg/m³ pollution threshold.
Argument Flow: The passage presents objective data collection, then provides the interpretive framework (the 15.0 threshold), and sets up for a data-driven conclusion about pollution levels across the metro area.
Step 2: Interpret the Question Precisely
This is a fill-in-the-blank question asking us to choose the best logical connector. The answer must create the right relationship between what comes before and after the blank.
Step 3: Prethink the Answer
- Compare each station's reading to the 15.0 threshold
- Downtown: \(18.7 \gt 15.0\) (above threshold)
- Suburban: \(12.3 \lt 15.0\) (below threshold)
- Industrial: \(24.1 \gt 15.0\) (above threshold)
- Residential: \(14.6 \lt 15.0\) (below threshold)
- Waterfront: \(16.2 \gt 15.0\) (above threshold)
- We have exactly 3 stations above the threshold (Downtown, Industrial, Waterfront) and 2 stations below (Suburban, Residential)
- The right answer should accurately state this 3-out-of-5 pattern or correctly identify which specific stations fall above or below the 15.0 mark
Only the Industrial Station recorded readings that significantly exceed the moderate pollution threshold.
✗ Incorrect
- Claims only Industrial Station 'significantly exceed' the threshold
- Ignores that Downtown \(18.7\) and Waterfront \(16.2\) also exceed \(15.0\)
- The word 'only' makes this factually wrong
The Suburban Station and Residential Station both recorded readings above the moderate pollution threshold.
✗ Incorrect
- States Suburban \(12.3\) and Residential \(14.6\) are both above \(15.0\)
- Both readings are actually below the threshold
- Completely contradicts the data
Three of the five monitoring stations recorded readings above the moderate pollution threshold.
✓ Correct
- Accurately states 'three of the five monitoring stations' exceed the threshold
- Matches our calculation: Downtown \(18.7\), Industrial \(24.1\), and Waterfront \(16.2\) all \(\gt 15.0\)
- Uses the data precisely without misrepresenting any readings
All monitoring stations except the Downtown Station recorded readings below the moderate pollution threshold.
✗ Incorrect
- Claims all stations except Downtown are below \(15.0\)
- Ignores that Industrial \(24.1\) and Waterfront \(16.2\) are also above threshold