Math Problem Statement

Compute the least-squares regression equation for the given data set. Use a TI-84 calculator. Round the slope and y-intercept to at least four decimal places.

Solution

To solve this least-squares regression problem using the given dataset:

Dataset:

xx106814-7-17-9
yy31303103-3-15

We need to calculate the regression line equation:
y^=mx+b\hat{y} = mx + b
where mm is the slope and bb is the y-intercept.


Steps to Compute:

  1. Input the data into a TI-84 calculator:

    • Go to STAT > EDIT.
    • Enter the xx-values in L1 and the yy-values in L2.
  2. Find the regression equation:

    • Press STAT > CALC > LinReg(ax+b) (option 4).
    • Select L1 and L2 as the data lists, then hit ENTER.
  3. Manual Calculation (if needed):

    • Use these formulas for slope (mm) and intercept (bb): 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=(y)m(x)nb = \frac{\sum(y) - m\sum(x)}{n} where nn is the number of data points.

Let me calculate these values for you now. numpy as np

Given data points

x = np.array([10, 6, 8, 14, -7, -1, 7, -9]) y = np.array([3, 1, 30, 31, 0, 3, -3, -15])

Number of points

n = len(x)

Calculations for regression

sum_x = np.sum(x) sum_y = np.sum(y) sum_xy = np.sum(x * y) sum_x_squared = np.sum(x ** 2)

Slope (m)

m = (n * sum_xy - sum_x * sum_y) / (n * sum_x_squared - sum_x ** 2)

Intercept (b)

b = (sum_y - m * sum_x) / n

m, bThe regression line equation is:
y^=1.3515x+1.5199\hat{y} = 1.3515x + 1.5199
(Rounded to 4 decimal places as requested.)

Would you like a step-by-step breakdown of the calculations or have any other questions?


Here are five related questions to explore:

  1. What is the interpretation of the slope mm in this context?
  2. How would the regression line change if an outlier were added to the dataset?
  3. Can you calculate the correlation coefficient rr for this data?
  4. What does the y-intercept bb represent for these values?
  5. How can you use this regression line to predict values for yy given specific xx?

Tip: Always plot the data points and the regression line to visually confirm the accuracy of your model.

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Math Problem Analysis

Mathematical Concepts

Least-squares regression
Linear equations
Data analysis

Formulas

Slope formula: m = (nΣ(xy) - ΣxΣy) / (nΣ(x^2) - (Σx)^2)
Intercept formula: b = (Σy - mΣx) / n

Theorems

Least-squares method

Suitable Grade Level

Grades 10-12