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Bilbo Baggins wants to save money to meet three objectives. First, he would like

ID: 2703798 • Letter: B

Question

Bilbo Baggins wants to save money to meet three objectives. First, he would like to be able to retire 30 years from now with retirement income of $31,500 per month for 25 years, with the first payment received 30 years and 1 month from now. Second, he would like to purchase a cabin in Rivendell in 10 years at an estimated cost of $415,000. Third, after he passes on at the end of the 25 years of withdrawals, he would like to leave an inheritance of $1,375,000 to his nephew Frodo. He can afford to save $4,000 per month for the next 10 years. If he can earn a 10 percent EAR before he retires and a 7 percent EAR after he retires, how much will he have to save each month in years 11 through 30?

Explanation / Answer

Lets work backwards. Bilbo needs a corpus after 30 yrs, which will give him 31500 pm for 25 yrs & then leave a corpus of 1375000

EAR = 7% after he reires

EAR = (1+i/12)^12 -1. Here m= 12 as we need monthly Interest rate

ie (1+i/12)^12 -1 = 7%

ie (1+i/12)^12 = 1+7% = 1.07

ie (1+i/12) = 1.07^(1/12) = 1.0057

ie i/12 = 1.0057 - 1 = 0.0057

so i = 12*0.0057 = 6.84%


No of periods = 25Yr*12month = 300 periods

So After 30 Yrs 1month, we have nper =300, Rate=6.84%/12, FV=1375000, PMT=31500


So Corpus at 30Y1M = PV(Rate,nper,pmt,fv)

= PV(6.84%/12,300,-31500,1375000)

= $4,272,029

SO at Y30, we need to find PV at 1Month

ie Corpus at Y30 = $4272029/(1+6.84%/12) = $4,247,816 ...(A)

He can afford to save $4,000 per month for the next 10 years. If he can earn a 10 percent EAR before he retires and a 7 percent EAR after he retires, how much will he have to save each month in years 11 through 30?

EAR = 10% before he reires

EAR = (1+i/12)^12 -1. Here m= 12 as we need monthly Interest rate

ie (1+i/12)^12 -1 = 10%

ie (1+i/12)^12 = 1+10% = 1.10

ie (1+i/12) = 1.10^(1/12) = 1.0080

ie i/12 = 1.0080 - 1 = 0.0080

so i = 12*0.0080 = 9.60%


Lets see how much he has after 10Yrs.

We have nper = 10*12 = 120 month, PMT=4000, Rate=9.6%/12, PV=0


SO At end of 10Yrs, he has =FV(Rate,nper,pmt,pv)

= FV(9.6%/12,120,-4000,0)

= $800,870

Second, he would like to purchase a cabin in Rivendell in 10 years at an estimated cost of $415,000.


So After buying Cabin for 415,000 at Y10, he has 800870-415000 = $385,870

SO This is his starting Corpus at Y10 = PV = $385,870 ....(B)


Now we have A&B to tell us that PV=$385,870, at Y30 FV= 4247816,

nper = 20*12 = 240 month, Rate = 9.6%/12


So Monthly saving = PMT(Rate,nper,pv,fv)

= PMT(9.6%/12,240,385870,4247816)

= $9,513


So he has to Save $9,513 every month from Y11 to Y30.