The annual birth and death rate in a country per 1000 are 39.4 and 19.4 respectively . the number of years B in which the population would be doubled assuming there is no emigration or immigration is Choose one:	A) 20	B) 25	C) B=30	D) B=35	E) B=40
Suppose the population of the country in current year is 1000.   So annual increase is  1000 + 39.4 - 19.4= 
<gadget id="calculator"> 1000 + 39.4 - 19.4</gadget>
<output>1_020</output>
1020   Hence every year there is an increase of 2%.   2000=1000(1+(2/100))^n   n=35 Answer is B=35.
<result>D</result>
The annual birth and death rate in a country per 1000 are 39.4 and 19.4 respectively . the number of years B in which the population would be doubled assuming there is no emigration or immigration is