Cpt maths help

cptstudent (education) (31 Points)

27 February 2014  

13.   The annual birth and death rates per 1000 are 39.4 and 19.4 respectively. The number of
years  in  which  the  population  will  be  doubled  assuming  there  is  no  immigration  or
emigration is


(a) 35 yrs. (b) 30 yrs. (c) 25 yrs (d) none of these

 

please explain with answers