Answer
1.33 % per year.
Work Step by Step
a) Using the points (2050, 10) and (2000,6), $\frac{dN}{dt} |_{t=2000}= \frac{10-6}{2050-2000} = \frac{4}{50} = 0.08$
Thus, in the year 2000, the population will grow by $0.08$ billion people.
b)
$\frac{\frac{dN}{dt}}{N} = \frac{0.08}{6} = 0.01333$, or about 1.33 % per year.
