I am stumped on this problem. On the surface, this seems like this should be relatively easy, middle school algebra. I cannot seem to come to a final equation that will work for my task at hand.
Given an X-coordinate value, what is the corresponding Y-coordinate value on the line? For example: I know the X value of 97.75%. How can I use an equation to come up with the Y-value that falls on the line, in the case of X=97.75% Y=25.
I have tried to come up with a formula for the line. When I try to solve for the slope of the first graph, I get 33.33. This doesn't seem correct to me. The graphs are from Excel. Within Excel I can click on the line, click "add trend line", and then click show equation. The equation that is displayed is Y= -25x + 125. When I plug in, for example, 97.75 and solve for Y I am left with a large negative number.
I feel like I am forgetting/missing some fundamentals here. Any help is appreciated. Again the goal is to come up with an equation so I can solve for the Y-coordinate value. "Given a percentage (X-axis), tell me the score (Y-axis)".
(97%, 0), (97.75%, 25), (98.50%, 50), (99.25%, 75), (100%, 100)
Graph 2: (80%, 0), (85%, 25), (90%, 50), (95%, 75), (100, 100)