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Average word problem

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3 Answers

Hi Theresa,
 
x1 = 1990
 
y1 = 3.1
 
x2 = 2007
 
y2 = 5.5
 
Rate  =  (y2 - y1)  /  (x2 - x1)
 
= (5.5 - 3.1) / (2007 - 1990)
 
use your calculator to solve this and that is your rate. God bless.
The average rate of change in broccoli consumption will be the slope of the straight line connecting the two points (1990, 3.1 lbs) and (2007, 5.5 lbs).  The slope is computed as the change in y (broccoli consumption) over the change in x (years).
 
slope (average rate of change of broccoli consumption) = (5.5-3.1)/(2007-1990) = 2.4/17 = 0.14 pounds (lbs) per year increase
 
To verify:
 
3.1 lbs+ (0.14 lbs per year)(17 years) = 3.1 lbs + 2.4 lbs = 5.5 lbs
The rate of change is equal to the change in "y" over the change in "x".

To find the average rate of change in this story problem, we need to find the change in consumption of broccoli divided by the change in the years (or number of years).  The consumption of broccoli is our "y" and the year is our "x."

So the rate of change in the consumption of broccoli = [(consumption in 2007)-(consumption in 1990)]/(2007-1990)

=(5.5-3.1)/(2007-1990)

Then solve the equation. The rate of change should be positive since the consumption of broccoli is increasing every year. It is important to remember that the rate of change is simply the slope.