The table gives the population of the world in the 20th century.

\begin{array}{|c|c|c|c|}
\hline
\mbox{Year} & \mbox{Population (in millions)} & \mbox{Year} & \mbox{Population (in millions)}\\ \hline
1900 & 1650 & 1960 & 3040 \\
1910 & 1750 & 1970 & 3710 \\
1920 & 1860 & 1980 & 4450 \\
1930 & 2070 & 1990 & 5280 \\
1940 & 2300 & 2000 & 6080 \\
1950 & 2560 & & \\
\hline
\end{array}

(a) Estimate the rate of population growth in 1920 by averaging the slopes of two secant lines (using the years 1910 and 1920, then 1920 and 1930).

Answer:

(b) Repeat the same process for 1980.

Answer:

You can earn partial credit on this problem.