posted by A.W. .
Is this right? Examine the rise in gasoline prices from 1997 to 2006. The price of regular unleaded gasoline price in January 1997 was $1.26 and in January 2006 was $2.31 (Bureau of Labor Statistics, 2006). Use the coordinates (1997, 1.26) and (2006, 2.31) to find the slope (or rate of change) between the two points. Describe how you arrived at your answer. Slope is y=mx+b. So I took m= 2006-1997/2.31-1.26= 1.05/9= .116666666= to about .12 cents per year.
Your slope equation is wrong. It is upside down in the first equation, but then you got it right with the numners. It is the change in price divided by the elapsed time, $1.05/9 yr = $0.117 per year.
The price has certainly not followed that straight line slope since 2006!