00:01
So in this question, they say this table gives the population of the world p of t in millions, where t is measured in years and t equals zero corresponds to the year in 1900.
00:11
In part a, they said estimate the rate of population growth in 1920 and 1980 by averaging the slopes of the two seacan lines.
00:20
And it looks like you have that correct.
00:23
So now we're going to move to part b, where they say use a graphing device to find a cubic function that models the data.
00:29
I'm going to let tb the year and i'm going to round all my values to five decimal places.
00:34
So i'm going to head to my calculator and i'm going to go into the stat menu and i'm going to edit.
00:41
And in l1, i'm going to put these xs, which go by tens from zero down to 110.
00:54
So 40, 50, 60, 70, 70, 80.
01:05
90, 100, 110.
01:11
And now i'm going to go over to l2.
01:13
What i'm going to put in my ys.
01:16
So my ys are 1650, 1750, followed by 1860, followed by 2070, and then it was 2300, and then it's 2560, and then it's 3040, and then it's 3040, 3710, and then it's 4 ,450, and then it was 5 ,280, followed by 6 ,080, and then finally, 6870.
02:17
Now i'm going to find a cubic regression.
02:19
So i'm going to go to stat, calculate.
02:22
Number six, a cubic regression, and let's see what we get for this cubic regression.
02:32
I get.
02:34
So my a is negative 2 .84900.
02:41
So what is happening there? that is going to be negative.
02:50
0 .00028, i believe, because i've got 2 .8 times 10 to the negative 4th...