Question 1083926
the percent of us drivers wearing seat belts in 2005 was 82%.
the percent of us drivers wearing seat belts in 2000 was 72%.


the difference between the percent in 2005 and the percent in 2000 is 82 - 72 = 10%.


the percent difference per year would be 10% / 5 = 2%.


2% is your slope.


the slope intercept form of a straight line is y = mx + b


m is the slope and b is the y-ingtercept.


when m is the change in the percent per year which is equal to 2.


the general formula becomes y = 2x + b


to find the y-intercept, replace x and y with the value from one of the points.


if you assume that x = 0 represents the year 2000, then:
x = 5 represents the year 2005, and:
x = 14 represents the year 2014.


one of your data points would be the percent in the year 2005.
that point would be (x,y) = 5,82


the formula of y = 2x + b becomes 82 = 2 * 5 + b
simplify to get 82 = 10 + b
solve for b to get b = 72


your y-intercept is 72


your slope intercept formula becomes y = 2x + 72


your y-intercept is the value of y when x = 0.


the graph of your equation would look like this:


<img src = "http://theo.x10hosting.com/2017/060601.jpg" alt="$$$" </>


the blue line is the graph of the equaiton.


the orance lines are just there to allow me to show you what the intersection points are.


when x = 0, y = 72
when x = 5, y = 82
when x = 14, y = 100


x = 0 represents the year 2000.
x = 5 represents the year 2005.
x = 14 represents the year 2014.


the value of y is in percent format, i.e. y = 72 means that y = 72%.


you can see that the formula accurately represents the data points given, assuming a linear equation which give you straight line growth.


when x = 0, you have 72% in 2000.
when x = 5, you have 82% in 2005.


the value of y = 100% when x = 14 is the extrapolation from the formula.