00:01
I'm going to use a graph and calculator to do this problem.
00:04
So first of all, we have a table of data, and we want to make a scatter plot.
00:08
So we go to stat and then edit, and we type all of the data into list one and list two, as you see i've already done.
00:16
So in the first list, we have the x values.
00:18
Those are the times.
00:20
And in the second list, we have the y values.
00:22
Those are the temperatures.
00:24
Now to get a scatter plot, what we can do is we can go into second y equals, which takes us to the stat plot menu.
00:31
Press enter to go into the menu for plot one, turn it on, and make sure it's scatterplot using list one and list two.
00:39
Now to get a good window, we go into the zoom menu and we go down to zoom 9, which is zoom stat, and the calculator will figure out a window for us.
00:50
Okay, the scatter plot is just the points that were plotted, not the curve that you see going now.
00:55
The curve is jumping ahead of me a little bit.
00:58
So the curve is the model, the equation that was given in the problem, was the cubic equation and i typed it into my y equals menu and then we see it plotted against the scatter plot.
01:12
So for part b, how well does the model fit the data? that model fits the data extremely well.
01:17
We see it touching all of those points in the scatter plot.
01:19
So that's a good thing.
01:21
Now using this model, we're going to approximate the times when the temperature is increasing and decreasing.
01:26
So i'm going to press trace.
01:28
And then i'm going to press the down arrow and now my cursor is on the model, not on the scatter plot.
01:33
So it's on the curve itself.
01:34
And what i'm going to do is move my cursor over to the left until it gets to right about the top point there...