解数学题，给分

小明以两种方式分别储蓄了2000元和1000元，一年后全部取出，扣除利息所得税后可得利息43.92元，已知这两种储蓄年利率为3.24% 问这两种储蓄的年利率各是百分之几？
设甲种的利率是x
2000x*80%+1000*（3.24%-x）*80%=43.92
x=0.81%
3.24%-0.81%=2.43%
30度的圆心角是周角的1/12

将一个圆沿半径剪开，再拼成一个近似长方形。已知这个长方形的周长是41.4厘米，那么，这个圆的周长和面积各是多少？
设圆的半径为R厘米
长方形的长=πR，宽=R
长方形的周长=2×（πR+R）=8.28R=41.4
R=5（厘米）
圆的面积=78.5平方厘米
圆的周长=31.4厘米

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