Funddamentals of Algebraic Modeling (recycling)

dv8anly

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Feb 5, 2008
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I am having a problem with solving slope problems I have tried to work out some of the problem here goes,

According to recycling records kept by the Environmental Protection Agency 38% of postconsumer newsprint was recycled in 1990, 45% in 1992, and 60% in 2001. Written in slope form y = 2.1x + 37

Where y = percent recycled (the percent is not converted to a decimal, so 45% would be enatered as 45 rather than 0.45) and x = the year number coded as 1990 = 1, 1992 = 3, 1994 = 5, and 2001 = 12.

Is the slope positive or negative? what does the slope tells us about the rate of postconsumer newsprint recycling?
45 = 2.1(3) + 37
45 = 6.3 + 37 The slope is positive, and It is increasing at a rate of 6.3 percent a year
Calculate the x-intercept year. What is it and what is the menaing of this point for these data?
5.8 = calculated year,
During what year will recycling theoretically reach 75% according to this model?
in 2004 this is all one question
 
dv8anly said:
Is the slope positive or negative?
The slope is positive. Why did you decide to evaluate it at year 3?

What does the slope tells us about the rate of postconsumer newsprint recycling?
It's increasing at a rate of 2.1%/year. Why did you decide to evaluate it at year 3?

Calculate the x-intercept year. What is it and what is the meaning of this point for these data?
0 = 2.1x + 37 ==> -17.62 ==> 1971ish. This model indicates we were recycling nothing back in 1971. How did you get 5.8?

During what year will recycling theoretically reach 75% according to this model?
75 = 2.1x + 37 ==> +18.095 ==> 2007ish. How did you get 2004?

this is all one question
I counted five questions.

Are we getting anywhere?

Note: This is a very bad model for general usage into the future. See what you get for year 31! What percentage are we recycling in the year 2020? :)
 
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