The world population in 1990 was 5.4 billion and in 1995 was 5.8 bilion. Use linear extrapolation to find.....

The world population in 1990 was 5.4 billion and in 1995 was 5.8 bilion. Use linear extrapolation to find the population in 2010.

Linear extrapolation just means that it follows a line. So you're given two points (1990, 5.4) and (1995, 5.8)

They lay on a line, so you need to find a y = mx + b
You know m = change in y/ change in x = (5.8 - 5.4) / (1995 - 1990) = .4/5 = .08

You can then plug in your points to find your

5.4 = .08*1990 + b
b = 153.8

Now you have your linearly extrapolated line y = .08x + 153.8
or

Population = .08*Year + 153.8

You should be able to solve for 2010 from there