For each of 13 adult nesting birds observed over a 24-hour period, the chart records the number of times the...
GMAT Graphics Interpretation : (GI) Questions
For each of 13 adult nesting birds observed over a 24-hour period, the chart records the number of times the bird left the nest from sunrise to sunset and the number of times the bird left the nest from sunset to sunrise. The chart also shows the trendline for the data.
On the basis of the information provided, select from each of the drop-down menus the option that creates the most accurate statement.
Owning The Dataset
Table 1: Text Analysis
| Text Component | Literal Content | Interpretation |
|---|---|---|
| Subject | 13 adult nesting birds | The dataset covers 13 mature birds that are currently nesting |
| Observation Period | Over a 24-hour period | Each bird was monitored continuously for one day and one night |
| Daytime Data | Number of times the bird left the nest from sunrise to sunset | For each bird, researchers counted how often the nest was left during daylight |
| Nighttime Data | Number of times the bird left the nest from sunset to sunrise | For each bird, researchers counted how often the nest was left during nighttime |
| Trendline | The chart also shows the trendline for the data | A line is drawn on the chart to show the overall data relationship |
Table 2: Chart Analysis
| Chart Component | What is Shown | Interpretation |
|---|---|---|
| Chart Type | Scatter plot with trendline | Visualizes the relationship between day and night departures |
| X-axis | Number of times bird left nest, sunset to sunrise (0-10) | Shows nighttime departures for each bird |
| Y-axis | Number of times bird left nest, sunrise to sunset (0-10) | Shows daytime departures for each bird |
| Data Points | 13 black dots (ranging between 1-9 on each axis) | Each dot represents one bird's paired day/night departure values |
| Trendline | Blue line, negative slope (approx. \(\mathrm{y = -0.8x + 8.5}\)) | Indicates a strong inverse relationship between day and night activity |
Key Insights
The dataset reveals a strong negative correlation between the number of daytime and nighttime nest departures among nesting birds: when birds leave the nest more often at night, they tend to leave less often during the day, and vice versa. This pattern, consistently present across all 13 birds, suggests a compensatory behavioral strategy. The maximum recorded departures for any individual bird in either period is 9.
Step-by-Step Solution
Question 1: Correlation Type Between Day and Night Departures
Complete Statement:
The chart shows [BLANK] correlation between the number of times an adult nesting bird leaves the nest from sunrise to sunset and the number of times that bird leaves the nest from sunset to sunrise.
Breaking Down the Statement
- Statement Breakdown 1:
- Key Phrase: correlation between the number of times an adult nesting bird leaves the nest from sunrise to sunset and ... from sunset to sunrise
Meaning: Identifies that the question is about the relationship between day (sunrise-sunset) and night (sunset-sunrise) departures for the birds.
Relation to Chart: The scatter plot axes are these two quantities for each observed bird.
Important Implications: A positive correlation would imply birds that leave a lot during the day also do so at night; a negative correlation would imply they're inversely related.
- Key Phrase: correlation between the number of times an adult nesting bird leaves the nest from sunrise to sunset and ... from sunset to sunrise
- Statement Breakdown 2:
- Key Phrase: The chart shows [BLANK] correlation
Meaning: The blank indicates we are to name the type of relationship shown by the chart.
Relation to Chart: The chart's trendline and clustering of points reveal the correlation.
Important Implications: Determining the sign of the correlation depends on the direction (slope) of the trendline.
- Key Phrase: The chart shows [BLANK] correlation
- What is needed: Whether the relationship between daytime and nighttime nest departures is negative or positive according to the chart.
Solution:
- Condensed Solution Implementation:
Examine the trendline and look for its slope direction (upward for positive, downward for negative) to determine the correlation. - Necessary Data points:
The equation of the trendline \(\mathrm{(y = -0.8x + 8.5)}\) and the general downward trend of points in the scatter plot.
Calculations Estimations:
Since the coefficient of x is -0.8, the slope is negative. The trendline goes down as it moves right, showing negative correlation.
Comparison to Answer Choices:
Between the choices ('negative', 'positive'), negative matches what is shown by the trendline.
FINAL ANSWER Blank 1: negative
Question 2: Maximum Number of Departures by Any Bird
Complete Statement:
During this 24-hour observation period, the maximum number of times any of the adult birds left the nest was [BLANK] times.
Breaking Down the Statement
- Statement Breakdown 1:
- Key Phrase: maximum number of times any of the adult birds left the nest
Meaning: We need the highest total (adding both day and night departures) for any single bird.
Relation to Chart: Each data point is a bird; its x (night) and y (day) coordinates sum to that bird's total departures.
- Key Phrase: maximum number of times any of the adult birds left the nest
- Statement Breakdown 2:
- Key Phrase: During this 24-hour observation period
Meaning: Sum of daytime and nighttime departures over one full day per bird.
Relation to Chart: Both axes together (per point) represent all departures for one bird in 24 hours.
- Key Phrase: During this 24-hour observation period
- What is needed: The largest sum of daytime and nighttime nest departures for any individual bird.
Solution:
- Condensed Solution Implementation:
Find the data point(s) where \(\mathrm{x + y}\) is the greatest (where x = night departures, y = day departures). - Necessary Data points:
Selected high-value data points: \(\mathrm{(3,9), (5,7)}\) yield \(\mathrm{3+9=12}\) and \(\mathrm{5+7=12}\) departures. Others yield lower sums.
Calculations Estimations:
Compute \(\mathrm{(1,8)=9, (2,7)=9, (3,9)=12, (5,7)=12}\). All other points are less than 12.
Comparison to Answer Choices:
Among the choices (9, 10, 11, 12), the maximum from the chart is 12.
FINAL ANSWER Blank 2: 12
Summary
By analyzing the scatter plot and its trendline, the correlation is negative, meaning as daytime departures increase, nighttime ones tend to decrease. To find the maximum number of departures, we combine day and night values for each bird; the greatest sum is 12, so the answer is 12.
Question Independence Analysis
The two questions are independent. The first relates only to the pattern (type of correlation) in the chart, while the second requires arithmetic to find the maximum departure sum for any one bird. Neither answer depends on the other.