00:01
Okay, to help us solve this problem, i drew a rough sketch of the graph given in the textbook, and i drew in tangent lines at the years 1930 and 1990.
00:09
So this is just a rough estimate, but i analyzed the first point in 1930 as roughly 6 million in population, and if you carry that line over a bit, i said in 1950, maybe that red tangent line is at 8 million.
00:23
So that will help us calculate the slope, because that's the change in y, which is 2 million people, over 50 years, and if we divide 2 million by 50, we'll get roughly 100 ,000 people per year.
00:42
So that means every year, this population is growing by 100 ,000 people or so.
00:48
But that's only at that moment of 1930, right? that's the instantaneous rate of change.
00:54
In 1990, i grew a tangent line and approximated the population was about 20 million at that time...