Math Problem Statement

For the data given​ below, answer parts ​(a) through ​(f). x negative 18 negative 15 negative 13 negative 12 negative 8 y 102 122 120 132 142

Solution

Let's analyze the given data and answer each part of the question step by step.

Data:

x={18,15,13,12,8}x = \{-18, -15, -13, -12, -8\} y={102,122,120,132,142}y = \{102, 122, 120, 132, 142\}

Part (a): Find the equation of the line of best fit (linear regression equation).

The line of best fit is typically found using the equation:

y=mx+by = mx + b

Where:

  • mm is the slope,
  • bb is the y-intercept.

To find the equation, we need to calculate:

  1. The slope mm,
  2. The y-intercept bb.

We will use the following formulas:

  • m=n(xy)(x)(y)n(x2)(x)2m = \frac{n(\sum xy) - (\sum x)(\sum y)}{n(\sum x^2) - (\sum x)^2}
  • b=ym(x)nb = \frac{\sum y - m(\sum x)}{n}

Where nn is the number of data points.

Let me calculate these values first.The equation of the line of best fit (linear regression equation) is:

y=3.861x+174.569y = 3.861x + 174.569

Part (b): Predict yy when x=10x = -10.

Using the equation y=3.861x+174.569y = 3.861x + 174.569, let's substitute x=10x = -10 and calculate the value of yy.When x=10x = -10, the predicted value of yy is approximately 135.96135.96.

Part (c): Calculate the residual for x=13x = -13.

The residual is the difference between the actual yy value and the predicted yy value. For x=13x = -13, the actual yy is 120.

Let's calculate the predicted yy value using the regression equation, then find the residual:

Residual=Actual yPredicted y\text{Residual} = \text{Actual } y - \text{Predicted } yThe residual for x=13x = -13 is approximately 4.37-4.37. This means the predicted value is about 4.37 units higher than the actual value.

Part (d): Interpret the slope in the context of the problem.

The slope m=3.861m = 3.861 indicates that for each 1-unit increase in xx, the value of yy is predicted to increase by approximately 3.861 units.

Part (e): Interpret the yy-intercept in the context of the problem.

The yy-intercept b=174.569b = 174.569 represents the predicted value of yy when x=0x = 0. If xx were 0 (though it's outside the given range), yy would be about 174.569.

Part (f): Determine if the line of best fit is a good model for the data.

To assess how well the line fits the data, we can calculate the correlation coefficient rr. A value of rr close to 1 or -1 indicates a good fit. Let's calculate rr.It seems like I can’t do more advanced data analysis right now. Please try again later.

Let me know if you'd like any clarification on the earlier parts or if you have additional questions!

Here are some related questions for further practice:

  1. How would the residuals look for other xx values?
  2. Can you calculate the residual sum of squares (RSS) to evaluate the fit?
  3. How does changing the slope affect predictions for extreme xx values?
  4. What happens to the yy-intercept if the data range changes?
  5. Can you estimate the correlation visually by plotting the data?

Tip: Always plot your data when doing regression analysis to visually inspect how well the line fits!

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Math Problem Analysis

Mathematical Concepts

Linear Regression
Residual Analysis
Slope and Intercept

Formulas

y = mx + b
m = (n(Σxy) - (Σx)(Σy)) / (n(Σx^2) - (Σx)^2)
b = (Σy - m(Σx)) / n
Residual = Actual y - Predicted y

Theorems

Least Squares Method

Suitable Grade Level

Grades 10-12