Originally Posted by

**LordMaximus** In a certain population the annual birth rate and annual death rate are 3.94% and 1.94% respectively.Find the number of years in which the population is doubled assuming that there is no immigration and emigration ?

now what i've tried is this

let x be the total population today

now we want 2x population

now we know that

total population in n years = total population born in n years - total population die in n years

=> 2x =x (1.0394)^n -x (1.0194)^n [ i've used the formula of compund interest which is derive by using a geometric series]

now what ???

after taking x common and canceling it , what should i do ?

please help me