<prompt> If annual growth rate of a population is 1.5-2, what number of years will be required to double the population70-47 years35-47 years35-28 years28-23 years  <response>: When crude death rate is substracted from crude bih rate , the net residual is current annual grow rate , exclusive of migration. When the annual growth rate of a population is 1.5 to 2.0, it takes 35-47 years to double the size of population. Reference : Park;s textbook of preventive and social medicine, 23rd edition, pg no: 481, table 5 