(a) Write a linear equation for Americans' income in y in terms of the year x using the points (1998, 7.4) and (1999, 7.8).

First - I used

**m= y2 - y1/ x2-x1**and substituted my points in to find the**slope**.Second - I used

**slope-intercept form**which is**y=mx + b**to find the**linear equation**so I can get the**y-intercept**.Third - I get my equation which is y=0.4x - 791.8

(b) Use the equation in (a) to estimate Americans' income in 2001.

First - Find y when x=2001 in

**slope-intercept form**. Put 2001 in for the**x value**in the equation from (a).Second - The answer will be 8.6 trillion which is only 0.1 off from 8.7 trillion.

(c) Use the equation in (a) to predict Americans' income in 2008.

First - Use the same steps as (b), but instead of 2001, use 2008.

Second - The answer will be 10.4 trillion.

(d) Superimpose a graph of the linear equation in (a) on a scatter plot of the data.

First - I used my graphing calculator to make my

**scatter plot**by plugging in all the points.Second - I pressed the [Y=] button and plugged in my equation from (a).

Third - You will see a line running through the first 2 points in your scatter plot and touching the other points.

By finding the slope and using the slope-intercept form to write a linear equation, I am able to estimate and predict Americans' income for any year that I want.

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