Indeterminable...

It depends on what the RATE of the increase is.

An infinite number of different curves can be plotted that intersect 2 common points.

e.g.; There is a difference between:

"The population doubled in size OVER 20 months" and

"The population doubles in size EVERY 20 months."

Based on the question, how do you justify the assumption that this is a straight line plot?

To make any sort of calculation, you need at least 3 points.

Even then your answer can only be calculated if the rate of change is constant.

3 years is 36 months or 20 * 1.8. The population will be 80,000 * 2 ^ 1.8

General equation: P = 80,000 • 2 ^ (t/20)

3 years = 36 months so t = 36

so evaluate 80000 • 2^(36/20)

A thought shared.

1 million.

Round to the nearest whole number as well.

Just want to see how to do it, thanks in advance.