请问永续年金是否涉及先付和后付的问题？

NO.PZ2017092702000012 问题如下 A sweepstakes winner mseleeither a perpetuity of £2,000 a month beginning with the first payment in one month or immeate lump sum payment of £350,000. If the annuscount rate is 6% compounmonthly, the present value of the perpetuity is: A.less ththe lump sum. B.equto the lump sum. C.greater ththe lump sum. C is correct.shown below, the present value (PV) of a £2,000 per month perpetuity is worth approximately £400,000 a 6% annurate compounmonthly. Thus, the present value of the annuity (is worth more ththe lump sum offer. A = £2,000 r = (6%/12) = 0.005 PV = (A/r) PV = (£2,000/0.005) PV = £400,000the present value of the“perpetuity”--永续年金，带入永续年金的公式 PV=A/r即可A=2,000， r=(6%/12)=0.005， PV=A/r=400,000 6% compounmonthly每期是一个月，利率是每月复利。为啥需要除以12呢

NO.PZ2017092702000012问题如下A sweepstakes winner mseleeither a perpetuity of £2,000 a month beginning with the first payment in one month or immeate lump sum payment of £350,000. If the annuscount rate is 6% compounmonthly, the present value of the perpetuity is:A.less ththe lump sum.B.equto the lump sum.C.greater ththe lump sum. C is correct.shown below, the present value (PV) of a £2,000 per month perpetuity is worth approximately £400,000 a 6% annurate compounmonthly. Thus, the present value of the annuity (is worth more ththe lump sum offer. A = £2,000 r = (6%/12) = 0.005 PV = (A/r) PV = (£2,000/0.005) PV = £400,000the present value of the“perpetuity”--永续年金，带入永续年金的公式 PV=A/r即可A=2,000， r=(6%/12)=0.005， PV=A/r=400,000 英文版的没看懂，想问下题目的中文翻译和中文解答

NO.PZ2017092702000012 问题如下 A sweepstakes winner mseleeither a perpetuity of £2,000 a month beginning with the first payment in one month or immeate lump sum payment of £350,000. If the annuscount rate is 6% compounmonthly, the present value of the perpetuity is: A.less ththe lump sum. B.equto the lump sum. C.greater ththe lump sum. C is correct.shown below, the present value (PV) of a £2,000 per month perpetuity is worth approximately £400,000 a 6% annurate compounmonthly. Thus, the present value of the annuity (is worth more ththe lump sum offer. A = £2,000 r = (6%/12) = 0.005 PV = (A/r) PV = (£2,000/0.005) PV = £400,000the present value of the“perpetuity”--永续年金，带入永续年金的公式 PV=A/r即可A=2,000， r=(6%/12)=0.005， PV=A/r=400,000 为什么不用(1+6%/12)^1的EAR公式计算有效年利率呢，不是每月复利一次吗，然后再用这个利率算年金的PV

NO.PZ2017092702000012问题如下A sweepstakes winner mseleeither a perpetuity of £2,000 a month beginning with the first payment in one month or immeate lump sum payment of £350,000. If the annuscount rate is 6% compounmonthly, the present value of the perpetuity is:A.less ththe lump sum.B.equto the lump sum.C.greater ththe lump sum. C is correct.shown below, the present value (PV) of a £2,000 per month perpetuity is worth approximately £400,000 a 6% annurate compounmonthly. Thus, the present value of the annuity (is worth more ththe lump sum offer. A = £2,000 r = (6%/12) = 0.005 PV = (A/r) PV = (£2,000/0.005) PV = £400,000the present value of the“perpetuity”--永续年金，带入永续年金的公式 PV=A/r即可A=2,000， r=(6%/12)=0.005， PV=A/r=400,000 请问什么时候需要从T1折现到T0，什么时候不需要？