If a population is growing at 2% how long will it take their population to double

35 years

Explanation:

The rule of 70 will be applied here as the growth is steady by some percentage. It is yearly growth in per-cent "/70 Knowing the doubling time for 2% from the chart it is easy to determine the years taken to double the population by the given rate.

Td (doubling time) at 2% is 35

Also,

dividing 70/2

= 35

So in 35 years the population will be double in 2 years at the rate of 2% increase.