The average price of gasoline in 1955 was $0.23 a gallon. In 2004 the average price of gas was $1.75 a gallon. How do you find the average rate of change of the price of gas per gallon in dollars per year?

1 Answer
Shantelle
Jul 21, 2018

The average rate of change is #$0.03# per gallon per year.

Explanation:

Let's create two coordinates/points with the given information. Typically, the time/year is on the #x# axis, so those are the #x#-coordinates.
#(1955, 0.23)# and #(2004, 1.75)#

To find the slope given two points, we use the formula #"rise"/"run"#, or #(y_2-y_1)/(x_2-x_1)#.

Plug in the given points into the formula:
#(1.75-0.23)/(2004-1955) = 1.52/49 ~~ 0.03#

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