the annual birth and death rate in a country per 1000 are 39.4 and 19.4 respectively . the number of years r in which the population would be doubled assuming there is no emigration or immigration is
n0 = 1000.0
n1 = 39.4
n2 = 19.4
t0 = 10.0 * 3.0
t1 = n1 - n2
t2 = t1 / n0
t3 = 100.0 - t0
t4 = t2 * 100.0
answer = t3 / t4
print(answer)