Math Problem Statement

find regression equation and final answer

The number of newly reported crime cases in a county in New York State is shown in the accompanying table, where x represents the number of years since 2002, and y represents number of new cases. Write the linear regression equation that represents this set of data, rounding all coefficients to the nearest hundredth. Using this equation, find the projected number of new cases for 2011, rounded to the nearest whole number.

Solution

To find the linear regression equation for this data, we need to calculate the slope (mm) and the y-intercept (bb) for a line in the form:

y=mx+by = mx + b

Steps to solve:

  1. Calculate the slope mm using: m=n(xy)xyn(x2)(x)2m = \frac{n \sum(xy) - \sum x \sum y}{n \sum(x^2) - (\sum x)^2} where nn is the number of data points.

  2. Calculate the y-intercept bb using: b=ymxnb = \frac{\sum y - m \sum x}{n}

  3. Substitute values into y=mx+by = mx + b to form the regression equation.

  4. Project the number of cases for 2011, which corresponds to x=9x = 9 (since 2011 is 9 years after 2002).

Let's calculate this step-by-step.The linear regression equation that represents this data is:

y=39.7x+1127.8y = 39.7x + 1127.8

Using this equation to project the number of new cases for the year 2011 (x=9x = 9), we find:

y=39.7×9+1127.81485y = 39.7 \times 9 + 1127.8 \approx 1485

Thus, the projected number of new cases for 2011 is approximately 1485.

Would you like a more detailed breakdown of these steps? Here are some related questions for further exploration:

  1. How do we interpret the slope and y-intercept in the context of this problem?
  2. What is the significance of using linear regression for predictions?
  3. Could we use a different type of regression if the data showed a non-linear pattern?
  4. How does rounding affect the accuracy of our predictions?
  5. What assumptions are we making with linear regression here?

Tip: Always check the correlation of your data points to see if a linear model is the best fit for predictions.

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Math Problem Analysis

Mathematical Concepts

Linear Regression
Algebra

Formulas

y = mx + b
Slope formula for linear regression: m = (nΣ(xy) - ΣxΣy) / (nΣ(x^2) - (Σx)^2)
Y-intercept formula: b = (Σy - mΣx) / n

Theorems

Linear Regression

Suitable Grade Level

Grades 10-12