Question

You deposited $350 in the bank with simple interest several years ago. You are keeping track of your account balance by drawing a graph. The points (3, 21) and (8, 56) are on the graph. What is the amount of interest you eam each year?

Answer 1

To find the amount of interest earned each year, we can use the points given on the graph: (3, 21) and (8, 56).

The first coordinate in each point represents the number of years, and the second coordinate represents the total amount of interest earned.

1. **Identify the interest earned at each point:**
- At year 3, you have earned \(21\) dollars.
- At year 8, you have earned \(56\) dollars.

2. **Calculate the increase in interest over the interval:**
- The change in interest from year 3 to year 8 is:
\[
56 - 21 = 35 \text{ dollars}
\]

3. **Calculate the change in time:**
- The change in years from year 3 to year 8 is:
\[
8 - 3 = 5 \text{ years}
\]

4. **Find the annual interest earned:**
- To find the amount of interest earned each year, divide the total increase in interest by the number of years:
\[
\text{Annual Interest} = \frac{\text{Change in Interest}}{\text{Change in Time}} = \frac{35}{5} = 7 \text{ dollars/year}
\]

Therefore, the amount of interest you earn each year is \(\boxed{7}\) dollars.