Math Problem Statement

Use your graphing calculator to find the equation of the trend line for the scatterplot below.

x

y

1

17

2

20

3

22

4

26

5

28

6

31

Solution

To find the equation of the trend line for the given scatterplot data, we can use the method of linear regression to find the line of best fit. The general equation of the trend line (or line of best fit) is y=mx+by = mx + b, where mm is the slope and bb is the y-intercept.

Here's the given dataTo find the equation of the trend line for the given scatterplot data, we can use the method of linear regression to find the line of best fit. The general equation of the trend line (or line of best fit) is y=mx+by = mx + b, where mm is the slope and bb is the y-intercept.

Here's the given

xy
117
220
322
426
528
631

We'll use the formulas for the slope (mm) and y-intercept (bb) of the line of best fit:

m=N(xy)xyN(x2)(x)2m = \frac{N \sum(xy) - \sum x \sum y}{N \sum(x^2) - (\sum x)^2}

b=ymxNb = \frac{\sum y - m \sum x}{N}

where NN is the number of data points.

First, we calculate the necessary sums:

x=1+2+3+4+5+6=21\sum x = 1 + 2 + 3 + 4 + 5 + 6 = 21

y=17+20+22+26+28+31=144\sum y = 17 + 20 + 22 + 26 + 28 + 31 = 144

xy=(117)+(220)+(322)+(426)+(528)+(631)=17+40+66+104+140+186=553\sum xy = (1 \cdot 17) + (2 \cdot 20) + (3 \cdot 22) + (4 \cdot 26) + (5 \cdot 28) + (6 \cdot 31) = 17 + 40 + 66 + 104 + 140 + 186 = 553

x2=12+22+32+42+52+62=1+4+9+16+25+36=91\sum x^2 = 1^2 + 2^2 + 3^2 + 4^2 + 5^2 + 6^2 = 1 + 4 + 9 + 16 + 25 + 36 = 91

Substituting these values into the formulas for mm and bb:

m=655321144691212=33183024546441=294105=2.8m = \frac{6 \cdot 553 - 21 \cdot 144}{6 \cdot 91 - 21^2} = \frac{3318 - 3024}{546 - 441} = \frac{294}{105} = 2.8

b=1442.8216=14458.86=85.26=14.2b = \frac{144 - 2.8 \cdot 21}{6} = \frac{144 - 58.8}{6} = \frac{85.2}{6} = 14.2

Therefore, the equation of the trend line is:

y=2.8x+14.2y = 2.8x + 14.2

Would you like any further details or have any questions about this calculation?

Here are five additional questions you can ask:

  1. How do I interpret the slope and y-intercept of the trend line?
  2. Can you show me how to plot this trend line on a scatterplot?
  3. What is the correlation coefficient for this data set?
  4. How can I use this trend line to make predictions?
  5. What are some common applications of trend lines in data analysis?

Tip: When performing linear regression, it's essential to check the residuals to ensure that your model is appropriate for the data. Residuals are the differences between the observed values and the values predicted by your model.

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Math Problem Analysis

Mathematical Concepts

Linear Regression
Scatterplots
Equation of a Line

Formulas

Slope formula
Y-intercept formula

Theorems

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Suitable Grade Level

High School