Chapter 8.9, Problem 6WE

To determine

To find: the approximate year.

Answer to Problem 6WE

In year $1925$ the population is $115$ millions.

Explanation of Solution

Given information:

The population is $115$ millions.

Calculation: let year is $x$ ,

Year	Population
$1920$	$106$
$x$	$115$
$1930$	$123$

Now, the difference,

  $\begin{array}{l}\frac{c}{10}=\frac{9}{17}\\ \frac{c}{10}=.52\text{ [divide]}\\ c\approx 5\text{ [multiply]}\end{array}$

Now, to find the value of year,

  $\begin{array}{l}x=1920+c\\ x=1920+5\text{ [substitute]}\\ x=1925\text{ [add]}\end{array}$

Thus, The value of year is $1925$ .