### 13-2: TEKS Practice

• 1. Eduardo's savings account earns 2.1% annual interest compounded monthly. If Eduardo has \$60.19 in the account and he deposits an additional \$20.00, how much interest will the account earn in a 1-month period? Round to the nearest cent.

• 2. Riley deposits \$225 each month into an account that earns 2.4% annual interest compounded monthly. The table shows the account balance at the end of each year to the nearest dollar.

• a. By the end of the fifth year, what amount has Riley deposited into the account?

• b. What amount of interest has the account earned?

• 3. Error Analysis Damian opens a savings account by depositing \$40.00 on the first day of a month. He deposits another \$40.00 on the first day of each month. The account earns 1.5% annual interest compounded monthly. Damian incorrectly completes a table as shown to find his balance after 4 months.

• a. Complete a table to find the correct balance after 4 months. Round to the nearest cent.

• b. What error did Damian make?

• 4. Reasoning Eva and Luke each have a savings account. Both deposit \$2,700 each year. Eva deposits \$2,700 at the end of each year. Luke deposits \$225 at the end of each month. Each account earns 2.4% annual interest compounded monthly. The table shows the rounded account balances at the end of each year.

• a. How much more interest does Luke earn after 4 years by making monthly deposits?

• b. Suppose Wyatt opens the same account but deposits \$1,350 every 6 months. How would Wyatt's balance at the end of year 4 compare to Eva's and Luke's balances? Round to the nearest cent. Explain.

• 5. Estimation Evan deposits \$200 in a savings account on the first day of each month. The account earns 2.7% annual interest compounded monthly. Evan wants to estimate the interest the account earns after 4 months. The first deposit earns interest for 4 months, the second for 3 months, the third deposit for 2 months, and the fourth deposit for 1 month, so Evan multiplies the interest earned the first month by 4+3+2+1=10.

• a. Does Evan's method underestimate or overestimate the interest? Explain.

• b. If the balance is \$804.51 after 4 months, what is the exact interest the account earns?

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