If cbr=25 , cdr=12 and nmr = 5 then find the population doubling time
Answers
Answer:

Measure of the Total Population Structure and Size
Population Size and Distribution
Population Ratios
Population Rates
Population Indices
Millenium Development Goals
Population Rates
Crude rates: A crude rate is used to describe the frequency of a demographic event across the total population, without regard to age or sex. The standard reference period is one year. Because the population is usually not the same at the beginning and end of the year, the denominator for crude rates is the average of the population at the beginning and end of the one year period. The numerator is the number of vital events (e.g., births, deaths) observed for the total population in the specified calendar year.
Crude Birth Rate (CBR): # of births per 1,000 persons in a population over a given period of time (i.e. 1 year). This rate is most often used when looking at fertility, though the crude measure does not account for important variations in population fertility such as sex ratios, age distributions, postponement or acceleration of marriage age, all of which can alter the way that the crude rate should be interpreted.
Example: In the town of Kolikouro, Mali, there were 5663 births. The total population was 149,442. The CBR is:
5663/149,442 * 1000 = 37.9
Ranges of CBR:
Least Developed: 40.4
Developing: 23.1
More Developed: 11.2
Crude Death Rate (CDR) : # of deaths per 1,000 persons in a population over a given period of time (i.e. 1 year). CDR is calculated in the same way as for CBR, but with deaths instead of births as the numerator.
Ranges of CDR:
Least Developed: 14.9
Developing: 7.8
More Developed: 10.2
crude r (rate of growth of a population) – Among locales where an estimate of the total population is available each year, estimating the growth of a population requires little more than dividing the change in population at the end of the year by the population at the beginning of the year. However, for most settings, vital statistics are collected during censuses only every few years. For these cases, we can estimate the average yearly population growth using the following formula, and solving for r.
Pt = P0 * ert where:
Pt is the population # at the last year for which there is data
P0 is the population # at the first year for which there is data
e is the natural logarithmic constant
r is the unknown annual rate of growth
t is the number of years between Pt and P0
Example: In 1950, the population in thousands for the Dominican Republic was 2,353. In 2000 (50 years later), it was 8,353. The rate of growth is estimated as follows:
8353 = 2353*e **r(50)
8353/2353 = e** r(50)
Take logs and re-arrange, to:
(ln 8353 – ln 2353 ) /50 = r
r = 2.54