Chapter 1.3, Problem 11E

To determine

To describe: The error in interpreting the slope in the context of the situation.

Answer to Problem 11E

Given slope is correct balance after 7 years will be 170.

Explanation of Solution

Given Information: - Given a linear graph.

Calculation:

As the line in the graph is passing through the points $(0,100)$ and $(4,140)$

Therefore, slope of line $=\frac{y_2-y_1}{x_2-x_1}$

  $=\frac{140-100}{4-0}$

  $=\frac{40}{4}=10$

The given slope is correct, let’s find the error in interpreting the slope.

Here, slope does not show the balance after 7 years, slope show how much will the balance grow in one year.

Now multiply the slope by 7 and we can find the balance grow in 7 years. Balance at the beginning was $100. After 7 years the balance.

  $\begin{array}{l}=100+7\times 10\\ =100+70\\ =170\end{array}$

Thus, slope is correct balance after 7 years will be 170.