Math Problem Statement

The annual profits for a company are given in the following table, where x represents the number of years since 2011, and y represents the profit in thousands of dollars. Write the linear regression equation that represents this set of data, rounding all coefficients to the nearest tenth. Using this equation, estimate the calendar year in which the profits would reach 248 thousand dollars. Years since 2011 (x) Profits (y) (in thousands of dollars) 00 9595 11 133133 22 131131 33 163163 Answer Attempt 2 out of 2

Regression Equation:

Final Answer:

Solution

Let's go through the steps to find the linear regression equation for the given data.

Step 1: Represent the Data

The data is presented as:

  • x=0,y=95x = 0, y = 95
  • x=1,y=133x = 1, y = 133
  • x=2,y=131x = 2, y = 131
  • x=3,y=163x = 3, y = 163

where xx is the number of years since 2011, and yy is the profit in thousands of dollars.

Step 2: Calculating the Linear Regression Equation

The formula for a linear regression equation is: y=mx+by = mx + b where:

  • mm is the slope of the line.
  • bb is the y-intercept.

To find the slope (mm), we use the formula: m=nxy(x)(y)nx2(x)2m = \frac{n \sum xy - (\sum x)(\sum y)}{n \sum x^2 - (\sum x)^2} and to find the intercept (bb): b=ymxnb = \frac{\sum y - m \sum x}{n} where nn is the number of data points.

Let's calculate each term:

  • n=4n = 4 (since there are 4 data points)
  • x=0+1+2+3=6\sum x = 0 + 1 + 2 + 3 = 6
  • y=95+133+131+163=522\sum y = 95 + 133 + 131 + 163 = 522
  • xy=(0)(95)+(1)(133)+(2)(131)+(3)(163)=0+133+262+489=884\sum xy = (0)(95) + (1)(133) + (2)(131) + (3)(163) = 0 + 133 + 262 + 489 = 884
  • x2=02+12+22+32=0+1+4+9=14\sum x^2 = 0^2 + 1^2 + 2^2 + 3^2 = 0 + 1 + 4 + 9 = 14

Substituting these values into the slope formula: m=4(884)(6)(522)4(14)(6)2=353631325636=40420=20.2m = \frac{4(884) - (6)(522)}{4(14) - (6)^2} = \frac{3536 - 3132}{56 - 36} = \frac{404}{20} = 20.2

Now calculate the intercept (bb): b=52220.2(6)4=522121.24=400.84=100.2b = \frac{522 - 20.2(6)}{4} = \frac{522 - 121.2}{4} = \frac{400.8}{4} = 100.2

Step 3: Write the Linear Regression Equation

The linear regression equation is: y=20.2x+100.2y = 20.2x + 100.2

Step 4: Estimate the Year When Profits Reach 248 Thousand Dollars

We need to find xx when y=248y = 248: 248=20.2x+100.2248 = 20.2x + 100.2 Solving for xx: 20.2x=248100.220.2x = 248 - 100.2 20.2x=147.820.2x = 147.8 x=147.820.27.3x = \frac{147.8}{20.2} \approx 7.3

Since xx represents the number of years since 2011: Estimated year=2011+7.32018\text{Estimated year} = 2011 + 7.3 \approx 2018

Final Answers:

  • Regression Equation: y=20.2x+100.2y = 20.2x + 100.2
  • Estimated Year: 2018

Would you like further details or have any questions about these steps?

Here are five related questions to consider:

  1. How do you interpret the slope of the regression line in this context?
  2. What is the significance of the y-intercept in the regression equation?
  3. How would the prediction change if the profit was expected to be 300 thousand dollars?
  4. What are some limitations of using linear regression for predicting future values?
  5. How could we measure the accuracy of this regression model?

Tip: When rounding coefficients in regression analysis, always consider the context and the degree of precision required for practical applications.

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Math Problem Analysis

Mathematical Concepts

Algebra
Linear Regression
Statistics

Formulas

Linear regression equation: y = mx + b
Slope formula: m = (nΣxy - ΣxΣy) / (nΣx^2 - (Σx)^2)
Intercept formula: b = (Σy - mΣx) / n

Theorems

Linear regression theory

Suitable Grade Level

Grades 10-12