Video Transcript
According to the data in the scatterplot, what was the approximate rate of population growth in the US per decade in millions? (Note: one decade equals 10 years).
Our 𝑦-axis gives us the population in millions. And our 𝑥-axis is the date. Notice that this graph begins at the date 1986. If we want to consider the per-decade growth, we need to know what 10 years after 1986 would be. That would be 1996. But this graph is counting by fours. And that means 1996 is going to fall halfway between 1994 and 1998. We can put a point on the line at the year 1996. 10 years after 1996 would be 2006. And we can put another mark on the line for 2006.
In 1986, the population was 240 million. In 1996, it was halfway between 260 and 270. So we could say that was 265 million. And then, in 2006, the dot falls on the 𝑦-axis on 290 million. And so an approximate rate of change would be from 240 to 265. That’s an addition of 25 million. And from 265 to 290 is another addition of 25 million.
Based on the data in our graph, we could say that the approximate rate of growth per decade in millions is 25 million.
