问题如下图：
选项：
A. 
B. 
C. 
解释：
请问如果支付是按年来支付，那么是否4%要转换为(1+0.04/12)的12次方。
NO.PZ2018062016000009问题如下 A perpetubonis a financiprothpays the same amount of money over infinite perioof time. Assume eamonth it pays $60, anthe annuscount rate of 4% compounmonthly. The present value of this bonis:A.$15,00B.$18,000C.untermineB is correct. The present value of a perpetuity is PV=A/r= $60/(4%/12)=$18,000.利率计算问题，问题如图
NO.PZ2018062016000009 问题如下 A perpetubonis a financiprothpays the same amount of money over infinite perioof time. Assume eamonth it pays $60, anthe annuscount rate of 4% compounmonthly. The present value of this bonis: A.$15,00 B.$18,000 C.untermine B is correct. The present value of a perpetuity is PV=A/r= $60/(4%/12)=$18,000. 题目中给出条件Assume eamonth it pays $60，就是说这个条件下，payment已经是按月度的了，与后面的y是一样的付息频率（按月），那为什么y还要除以12？我理解是直接用60/0.04就可以了。求老师解答。
NO.PZ2018062016000009问题如下A perpetubonis a financiprothpays the same amount of money over infinite perioof time. Assume eamonth it pays $60, anthe annuscount rate of 4% compounmonthly. The present value of this bonis:A.$15,00B.$18,000C.untermineB is correct. The present value of a perpetuity is PV=A/r= $60/(4%/12)=$18,000.请问给就是月付，利息也按月复利，此时为什么还要除以12？
NO.PZ2018062016000009问题如下A perpetubonis a financiprothpays the same amount of money over infinite perioof time. Assume eamonth it pays $60, anthe annuscount rate of 4% compounmonthly. The present value of this bonis:A.$15,00B.$18,000C.untermineB is correct. The present value of a perpetuity is PV=A/r= $60/(4%/12)=$18,000.为啥4%不用折算成ear再除以12？什么时候需要折成ear什么时候又不用，可以具体讲讲么
NO.PZ2018062016000009 =A/r= $60/(4%/12)=$18,000? 当我使用同样的公式计算$60/(4%/12)，我的计算结果是$18181.812，这道题是错误吗？
