Problem
An account invested in a money market fund grew from $\$ 73,263.43$ to $\$ 73,554.76$ in a month. What was the interest rate to the nearest tenth? What was the interest rate? $\%$ (Do not round until the final answer. Then round to the nearest tenth as needed.)
Solution
Step 1 ：\(73,554.76 - 73,263.43 = 291.33\)
Step 2 ：\(\frac{291.33}{73,263.43} * 100 = 0.3976\%\)
Step 3 ：\(\text{Rounding to the nearest tenth, the interest rate is } 0.4\%\)
Step 4 ：\(73,263.43 * 0.004 + 73,263.43 = 73,554.76\)
Step 5 ：\(\boxed{0.4\%}\)
