Question

In $2005$, for each of the $14$ million people present in a country, $0.028$ were born and $0.008$ died during the year. Using exponential equation, the number of people present in $2015$ is predicted as

• A. $25$ millions
• B. $17$ millions
• C. $20$ millions
• D. $18$ millions

Answer 1

Answer: (B)

$17$ millions

Answer 2

Exponential equation gives population growth rate as $\frac{dN}{dt}=rN$ Here, $r =$ intrinsic rate of natural increase $N =$ size of original population $\frac{dN}{dt}=$ Increase in population size per unit time ($1$ year in this case) $r$ is the difference between birth and death rate. $r = 0.028 -0.008 = 0.02$ $\therefore \frac{dN}{dt}=0.02\times14$ million $= 0.28$ million Over $10$ years $(2005 - 2015)$, this number will become $= 2.8$ million. Expected population in $2015 = (14 + 2.8)$ million $= 17$ million (approx.)