求年利率的数学题：小明把1000元压岁钱存入银行，两年后取出本金和利息后一共1043.2元。你知道年利率是多少吗？（利息税按20%计算）

数学题解答：要注意存期是两年，先算出实得利息，再算出扣税前的利息，再用利息除以存的年数和本金。

1043.2-1000=43.2 （元）

43.2÷(1-20%)＝54（元）

54÷2÷1000=2.7%

答：年利率是2.7%。

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