Project - would you please check my answers?
I am working on a project and my linear equation came out to be:
y = 1502.9x - 2847386
This project is about waste and recycling so the equation came from a table that gave a few years and the tons of waste in each of those years.
1) We have to state the slope, so I am saying that the slope is 1502.9 which means that on average there are 1502.9 tons of waste each year. Is this correct?
2) Does the equation have a y-intercept? I am saying that my y-intercept is (0, -2857386).
The question asks what does this mean in terms of the context of the problem.
I am thinking that since our years begin in 1990, it means that that is how much is already present in the landfill? But I'm not entirely sure because I don't understand the negative sign -- please help!
3) Does your equation have an x-intercept? If so, solve to find the x-intercept. I'm really unclear about this one because to me it would seem there would not be an x-intercept since this would be the beginning of time, or, you can't have no trash.
4 answers
#2 the y-intercept is negative. If the records started in 1990, then that is just a back-projection on the slope of the line. Not really much meaning in this context.
#3 the x-intercept is where y=0 (x=1894). That could be when records started, but it is more likely that they started keeping records sometime after that year, like 1990. The line is just a best-fit for the records on hand. It is very likely that before 1990 the rate of growth was much slower, causing the graph to flatten out to the left.