Question

the crude growth rate, r, of a population is calculated by
a. multiplying the existing population size by life expectancy
b. dividing the crude birth rate by 2
c. dividing the doubling time by 70
d. adding the crude birth rate to the crude death rate
e. subtracting the crude death rate from the crude birth rate

Explanation:

To determine the correct method for calculating the crude population growth rate (\( r \)):

• Option A: Multiplying population size by life expectancy is not related to growth rate calculation.
• Option B: Dividing crude birth rate by 2 is incorrect; growth rate involves birth and death rates.
• Option C: Dividing doubling time by 70 is for estimating doubling time from growth rate (Rule of 70), not the reverse.
• Option D: Adding birth and death rates is wrong; growth rate is the net change from births minus deaths.
• Option E: The crude growth rate \( r \) is calculated as \( \text{Crude Birth Rate (CBR)} - \text{Crude Death Rate (CDR)} \), so subtracting CDR from CBR is correct.

Answer:

E. subtracting the crude death rate from the crude birth rate