Math Problem Statement

Suppose we want to use data on square footage to predict home sale prices. An equation that fits the data below reasonably well is

Predicted Selling Price=29.74+0.14(Square Footage).

In order to find the sum of squared errors for this data, we have constructed the following table.

Housing Prices and Square Footage Observed Selling Price (Thousands of Dollars) Observed Square Footage Predicted Selling Price (Thousands of Dollars) Error Squared Error 195.5 1210 199.14 − 3.64 13.2496 261.0 1670 263.54 − 2.54 6.4516 236.3 1496 239.18 − 2.88 8.2944 256.8 1658 261.86 − 5.06 25.6036 173.6 1021 172.68 0.92 0.8464 290.2 1879 292.80 − 2.60 6.7600 210.7 1281 209.08 1.62 2.6244 294.9 1871

Find the missing values in the table for an observed selling price of 294.9 and square footage of 1871 . Round your answers to two decimal places, if necessary.

Solution

To find the missing values for the observed selling price of 294.9 and square footage of 1871, we need to calculate the predicted selling price, the error, and the squared error.

We are given the equation for the predicted selling price:

Predicted Selling Price=29.74+0.14×(Square Footage)\text{Predicted Selling Price} = 29.74 + 0.14 \times (\text{Square Footage})

Step 1: Calculate the predicted selling price

Using the square footage of 1871, we can plug this value into the equation:

Predicted Selling Price=29.74+0.14×1871\text{Predicted Selling Price} = 29.74 + 0.14 \times 1871 Predicted Selling Price=29.74+261.94=291.68 (Thousands of Dollars)\text{Predicted Selling Price} = 29.74 + 261.94 = 291.68 \text{ (Thousands of Dollars)}

Step 2: Calculate the error

The error is the difference between the observed selling price and the predicted selling price:

Error=Observed Selling PricePredicted Selling Price\text{Error} = \text{Observed Selling Price} - \text{Predicted Selling Price} Error=294.9291.68=3.22 (Thousands of Dollars)\text{Error} = 294.9 - 291.68 = 3.22 \text{ (Thousands of Dollars)}

Step 3: Calculate the squared error

The squared error is simply the square of the error:

Squared Error=(Error)2\text{Squared Error} = (\text{Error})^2 Squared Error=(3.22)2=10.3684\text{Squared Error} = (3.22)^2 = 10.3684

Summary of Missing Values:

  • Predicted Selling Price: 291.68 (Thousands of Dollars)
  • Error: 3.22 (Thousands of Dollars)
  • Squared Error: 10.37 (Thousands of Dollars)

Would you like further details or have any questions on the process? Here are some related questions for your learning:

  1. How would you calculate the sum of squared errors for all the data points?
  2. What does the squared error tell us about the accuracy of the prediction?
  3. How would you interpret the coefficients in the linear equation for predicting home prices?
  4. What other factors could influence home prices aside from square footage?
  5. How can the residual sum of squares (RSS) help in evaluating the performance of a model?

Tip: When working with regression models, always check for outliers, as they can have a disproportionate impact on the model’s performance.

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Math Problem Analysis

Mathematical Concepts

Linear Regression
Prediction
Error Analysis
Squared Error

Formulas

Predicted Selling Price = 29.74 + 0.14 × Square Footage
Error = Observed Selling Price - Predicted Selling Price
Squared Error = (Error)^2

Theorems

Least Squares Regression
Error Minimization

Suitable Grade Level

Grades 9-11