Dongdong's father deposited 20,000 yuan in the bank for three years. After the maturity date, Dad obtained a total of 23,240 yuan in principal and interest from the bank. What is the annual interest rate for a three-year time deposit?
东东的爸爸将20000元存入银行，定期三年．到期后爸爸从银行取得本金和利息共23240元．三年定期存款的年利率是百分之几？
<gadget id="calculator">23_240 - 20_000</gadget>
<output>3_240</output>

<gadget id="calculator">3_240 / 20_000 / 3</gadget>
<output>27/500 = around 0.054</output>

<result>27/500 = around 0.054</result>