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.