The Bureau of Census record in 2000 shows that the population in the country doubled compared to that of 1980. In what year will the population triple assuming that the rate of increase in population is proportional to the population?

this is just like the previous problem. But you can leave it in the form

y = c e^(kx)
and then find k, and then find x when y=3

or, e^(ln2/20 * x) = 3