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Lines of best fit

Phobosdeimos

New member
Apr 3, 2015
1
The average annual exchange rate in Canada for the US Dollar from 1998-2007 is shown in the following table. Draw a scatter plot, without using graphing technology

Year Exchange Rate
1998 .67
1999 .67
2000 .70
2001 .74
2002 .80
2003 .81
2004 .86
2005 .87
2006 .90
2007 .99

To determine the Slope I did the following
1998 - 2006 = -8
.67 - .90 = -.23

y= .23
Divide
x = -8

The slope of the line is - 0.02875

I then tried the y intercept
y = mx +b

.90 = - 0.02875 (2006) + b

.90 = -57.6725 + b

.90
- 57.6725 = b

b = 58.5725

This is what I came up for the y Intercept (58.5725)

Doesn't seem right to me

Please Help

Phobos
 

Sudharaka

Well-known member
MHB Math Helper
Feb 5, 2012
1,621
The average annual exchange rate in Canada for the US Dollar from 1998-2007 is shown in the following table. Draw a scatter plot, without using graphing technology

Year Exchange Rate
1998 .67
1999 .67
2000 .70
2001 .74
2002 .80
2003 .81
2004 .86
2005 .87
2006 .90
2007 .99

To determine the Slope I did the following
1998 - 2006 = -8
.67 - .90 = -.23

y= .23
Divide
x = -8

The slope of the line is - 0.02875

I then tried the y intercept
y = mx +b

.90 = - 0.02875 (2006) + b

.90 = -57.6725 + b

.90
- 57.6725 = b

b = 58.5725

This is what I came up for the y Intercept (58.5725)

Doesn't seem right to me

Please Help

Phobos
Hi Phobosdeimos,

The question tells you to draw a scatter plot according to the given data. Your slope and y-intercept is for the straight line that goes through the two points $(1998, 0.67)$ and $(2006, 0.90)$. If the points given approximately lie on a straight line you can find the best fitting straight line using linear regression as below.

Introduction to Linear Regression
 

priyash

New member
Jun 29, 2020
1
Very interesting to read this article.I would like to thank you for the efforts you had made for writing this awesome article. This article inspired me to read more. keep it up.
<a href="https://www.excelr.com/blog/data-science/statistics-for-data-scientist/Correlation-vs-covariance">Correlation vs Covariance</a>
<a href="https://www.excelr.com/blog/data-science/regression/simple-linear-regression">Simple linear regression</a>
<a href="https://www.excelr.com/mock-interview/data-science-interview-questions">data science interview questions</a>
 

Country Boy

Well-known member
MHB Math Helper
Jan 30, 2018
469
I am confused. You titled this "Line of best fit" and show how you have tried to calculate a slope and y-intercept. But the problem, at least the part you show, says nothing about any line! It asks only for a scatter plot. Do you know what that is?