1 Keith opened a savings account with \( \$ 400 \) and was paid simple interest at an annual rate of \( 4 \% \). When Keith closed the account, he was paid \( \$ 64 \) in in How long was the account open for, in years? If necessary, refer to the list of financial formulas.

To determine how long Keith's savings account was open, we'll use the **simple interest formula**: \[ \text{Interest} (I) = \text{Principal} (P) \times \text{Rate} (r) \times \text{Time} (t) \] **Given:** - **Principal (P):** \$400 - **Annual Interest Rate (r):** 4% or 0.04 (in decimal) - **Interest Earned (I):** \$64 **Plugging the values into the formula:** \[ 64 = 400 \times 0.04 \times t \] **Calculate the product of Principal and Rate:** \[ 400 \times 0.04 = 16 \] So, the equation simplifies to: \[ 64 = 16 \times t \] **Solve for Time (t):** \[ t = \frac{64}{16} = 4 \text{ years} \] **Answer:** Keith's account was open for **4 years**.