Sarah has $480 in her savings account earning 4/1/4% interest. How much interest will she earn in 2/1/2 years? How much money will be in the account after 2/1/2 years?

First year -- $480 x .0425 = $20.40
..................$480 + 20.40 = $500.40

Second year -- $500.40 x .0425 = $21.27
...............$500.40 + 21.27 = $521.67

Half year -- $521.67 x .0425 = $22.17/2
............$521.67 + $11.09 = $532.76

To calculate the interest Sarah will earn in 2 1/2 years, you first need to determine the interest earned for each year individually.

Start with the first year:
Interest for the first year = $480 x 4 1/4% = $480 x 0.0425 = $20.40

To find the total amount of money in the account after one year, add the interest earned to the initial amount:
Total after one year = $480 + $20.40 = $500.40

Moving on to the second year:
Interest for the second year = $500.40 x 4 1/4% = $500.40 x 0.0425 = $21.27

To find the total amount of money in the account after two years, add the interest earned to the balance after one year:
Total after two years = $500.40 + $21.27 = $521.67

Finally, calculate the interest for the half year:
Interest for the half year = $521.67 x 4 1/4% = $521.67 x 0.0425 = $22.17/2 = $11.09

To obtain the final amount in the account after 2 1/2 years, add the interest earned for the half year to the balance after two years:
Total after 2 1/2 years = $521.67 + $11.09 = $532.76

Therefore, Sarah will earn $11.09 in interest over the course of 2 1/2 years, and the total amount in her account after this time period will be $532.76.