Math Problem Statement

Consider the following:

X

33

57

75

98

110

Y

201

224

181

129

111

  1. What is slope of the regression line predicting Y from X,rounded to 2 decimal places?

  2. What is the intercept of the regression line predicting Y from X, rounded to 2 decimal places?

  3. What is the correlation between X and Y, rounded to 2 decimal places?

Solution

To solve this, we will use simple linear regression, which fits a line to the data to predict YY based on XX. The equation of a regression line is:

Y=a+bXY = a + bX

Where:

  • aa is the intercept
  • bb is the slope
  • The correlation coefficient (r) measures the strength and direction of the linear relationship.

The slope bb is calculated as:

b=n(XY)(X)(Y)n(X2)(X)2b = \frac{n(\sum XY) - (\sum X)(\sum Y)}{n(\sum X^2) - (\sum X)^2}

The intercept aa is calculated as:

a=Yb(X)na = \frac{\sum Y - b(\sum X)}{n}

Where nn is the number of data points.

The correlation coefficient rr is calculated as:

[ r = \frac{n(\sum XY) - (\sum X)(\sum Y)}{\sqrt{[n(\sum X^2) - (\sum X)^2][n(\sum Y^2) - (\sum Y)^2]}} ]

I'll calculate the values now.1) The slope of the regression line predicting YY from XX is 1.38-1.38.

  1. The intercept of the regression line is 271.81271.81.

  2. The correlation between XX and YY is 0.89-0.89, indicating a strong negative linear relationship.

Would you like any further details on the calculations or the interpretation?

Here are 5 follow-up questions to extend understanding:

  1. What does the slope of 1.38-1.38 indicate about the relationship between XX and YY?
  2. How can we interpret the negative correlation of 0.89-0.89?
  3. What would happen to the line if the intercept were higher or lower?
  4. Can we predict YY if XX is outside the provided range?
  5. What is the meaning of the residuals in a regression line?

Tip: A negative slope in regression implies that as the predictor variable increases, the response variable decreases.

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Math Problem Analysis

Mathematical Concepts

Statistics
Linear Regression
Correlation

Formulas

Slope: b = [n(ΣXY) - (ΣX)(ΣY)] / [n(ΣX^2) - (ΣX)^2]
Intercept: a = [ΣY - b(ΣX)] / n
Correlation: r = [n(ΣXY) - (ΣX)(ΣY)] / √{[n(ΣX^2) - (ΣX)^2][n(ΣY^2) - (ΣY)^2]}

Theorems

Linear Regression Theorem
Correlation Coefficient Formula

Suitable Grade Level

Grades 10-12, Introductory College