Math Problem Statement

Match each graph with its correlation coefficient. Explain your reasoning in at least 3 full sentences.

Solution

To solve this problem, let’s carefully analyze each graph and match it to its correlation coefficient based on the strength and direction of the linear relationship between the variables.

  1. Graph A: The points in this graph form a clear upward linear pattern with very little scatter. A positive, strong correlation is evident. Thus, the correlation coefficient is closest to r = 0.98.

  2. Graph B: This graph shows a downward trend, meaning the correlation is negative. The points are tightly clustered along the line, which suggests a strong negative correlation. Therefore, the correlation coefficient is r = -0.97.

  3. Graph C: The points in this graph are scattered with no clear upward or downward trend, indicating no correlation between the variables. This means the correlation coefficient is approximately r = 0.

  4. Graph D: Here, the points show a weak positive trend. While the points are somewhat spread out, there is still a general upward direction, indicating a moderate positive correlation. Thus, the correlation coefficient is r = 0.69.

Final Matching:

  • A: r = 0.98
  • B: r = -0.97
  • C: r = 0
  • D: r = 0.69

Explanation:

The correlation coefficient rr measures the strength and direction of a linear relationship. A value close to 11 or 1-1 indicates a strong correlation, while a value near 00 suggests no correlation. Graph A has a strong positive correlation, Graph B a strong negative correlation, Graph C no correlation, and Graph D a moderate positive correlation.


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Related Questions:

  1. What does a positive or negative correlation coefficient signify?
  2. How do you calculate a correlation coefficient rr for a set of data points?
  3. What are examples of strong and weak correlations in real-life data?
  4. How does the scatterplot pattern reflect the value of rr?
  5. What would the graph look like if r=1r = -1 or r=1r = 1?

Tip:

A strong correlation (positive or negative) means the points are closely clustered around a straight line, while weak or no correlation shows scattered points.

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Math Problem Analysis

Mathematical Concepts

Correlation Coefficient
Scatterplots
Linear Relationships

Formulas

Correlation coefficient r = (Σ(xy) - (Σx)(Σy)/n) / sqrt((Σx² - (Σx)²/n)(Σy² - (Σy)²/n))

Theorems

A positive r indicates an upward trend; a negative r indicates a downward trend. Values close to 1 or -1 represent strong correlations, and r ≈ 0 represents no correlation.

Suitable Grade Level

Grades 8-10