Answer
(c)
Work Step by Step
First convert birth and death rates to the same units:
Births:
$2$ per $100$ people $
= 20$ per $1000$ people
Deaths:
$5$ per $1000$ people $=5$ per $1000$ people
Calculate the population growth rate (let that be $r$):
$r=\text{birth rate}−\text{death rate}=
20-5=15$ per $1000=0.015$ per year
Use the Rule of $70$ to estimate doubling time:
$\text{Doubling time}=\frac{70}{r (\%)}=\frac{70}{1.5}\approx 46.7\approx 47$ years
The answer is (c).
