In the nineteenth century Sweden had a yearly population growth peaking at 1.2%?

Question

What was its doubling rate and how is this problem figured out?

Answer 1

Rule of 72.  72 divided by 1.2 equals 60.  So the doubling rate is 60 years.

The Rule of 72 is an approximation that works pretty well.

More precisely:

e^T(.012)=2

T(.012)=ln2

T=ln2/.012=57.6

T=time to double=57.6 Years.