the annual birth and death rate in a country per 1000 are 39.4 and 19.4 respectively . the number of years in which the population would be doubled assuming there is no emigration
or immigration is
Suppose the population of the country in current year is 1000.
So annual increase is 1000 + 39.4 - 19.4=1020
Hence every year there is an increase of 2%.
n=35 Answer is D. (But Calculation is somewhat tedious.) Anything simple than this?Consider KUDOS if its helpful.