Answer:
The birth rate refers to an average number of births in one year per thousand individuals in the population at mid-year.
BR = (total birth in an annum / total population in mid year) * 1000
BR = (50000 / 1000000) * 1000 = 50
Death rate refers to an average number of death in an annum per thousand individuals in a population at mid year. Thus,
DR = (total death / total population in mid year) * 1000
DR = (10000 / 1000000) * 1000 = 10
Annual population growth rate or APGR is calculated as:
APGR = (Birth rate - Death rate) / Death rate
APGR = (50 - 10) / 10 = 4.0 %
Doubling time is the whole sum time needed for a population to get double in size. It is calculated as DT = ln (2) / growth rate
70 / 4.0 = 17.5 years
Thus, population will get double in 17.5 years.
Adjusted (true) growth rate is equal to APGR + (NMR / Death rate)
And NMR = [(immigrants -emigrants) / total population] * 1000
NMR = [(5000 - 20000) / 1000000] * 1000 = -15
Thus, Adjusted (True) growth rate = 4.0 + (-15 /10) = -6%
The adjusted (true) doubling time = ln (2) / Adjusted growth rate
= 70 / -6 = -11.66
This negative sign shows that it will never get double in such situation.
