1. **State the problem:** Sandra deposited 2500 in a savings account that earns compound interest annually. After 4 years, the amount is 2937.91. We need to find the annual interest rate $r$ (as a decimal) and express it as a percentage to 1 decimal place. 2. **Formula used:** The compound interest formula is: $$ A = P(1 + r)^t $$ where: - $A$ is the amount after $t$ years, - $P$ is the principal (initial deposit), - $r$ is the annual interest rate (decimal), - $t$ is the time in years. 3. **Substitute known values:** $$ 2937.91 = 2500(1 + r)^4 $$ 4. **Isolate $(1 + r)^4$:** Divide both sides by 2500: $$ \frac{2937.91}{2500} = \cancel{\frac{2500}{2500}}(1 + r)^4 $$ $$ 1.175164 = (1 + r)^4 $$ 5. **Solve for $1 + r$ by taking the fourth root:** $$ 1 + r = \sqrt[4]{1.175164} $$ 6. **Calculate the fourth root:** $$ 1 + r \approx 1.041 $$ 7. **Find $r$:** $$ r = 1.041 - 1 = 0.041 $$ 8. **Convert to percentage:** $$ r = 0.041 \times 100 = 4.1\% $$ **Final answer:** The annual interest rate is **4.1%** to 1 decimal place.