SOLUTION: A man is planning to retire in 25 years. He wishes to deposit a regular amount every three months until he retires so that, beginning one year following his retirement, he will

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Question 1142108: A man is planning to retire in 25 years. He
wishes to deposit a regular amount every
three months until he retires so that,
beginning one year following his retirement,
he will receive annual payments of $32,000
for the next 10 years. How much must he
deposit if the interest rate is 8%
compounded quarterly?

Found 2 solutions by Alan3354, ikleyn:
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
No sane person can plan 25 years ahead.
-------
For example,
---
In 25 years I'll have $xxxxx.
But I died 23 years from now.

Answer by ikleyn(52775) About Me  (Show Source):
You can put this solution on YOUR website!
.

I will assume that the person deposits a regular amount at the end of every quarter during 25 years

and then withdraws $32000 at the beginning of each of the next 10 years, making the account empty after 10 withdrawals.


    Different schemes are possible, and each such a scheme requires a separate consideration - but what I propose 

    is natural and reasonable, making the problem correctly and precisely formulated.


Solution

            I will solve this problem in two steps.

Step  1.

First, I will determine how much money X should be accumulated on the account during 25 years,
in order for to have enough to withdraw $32000 at the beginning of each of the next 10 years.


By withdrawing $32000 at the beginning of each year, the account (the remaining money) still earns 8% per annum compounded quarterly.


It means that effective annual rate for this account is  %281+%2B+0.08%2F4%29%5E4 = 1.082432 compounded annually.


So, when you withdraw money during 10 years from your account, it still earns with effective rate of 1.082432 per year compounded annually.

Thus, it works as if it would be compounded annually at the rate of 8.2432%.


Such scheme withdrawing money was considered at the lesson  
    Withdrawing a certain amount of money periodically from a compounded saving account  
in this site.


The formula for the account value before it starts discharging is

    M = 32000%2A%28%28%281-%281%2B0.082432%29%5E%28-10%29%29%29%2F0.082432%29,     (1)


which gives us the value at the account of

    M  = 212387 dollars.


Step  2.

Now I am in position to determine how much the person should deposit each quarter during 25 years 

to accumulate  212387 dollars in his account. The number of quarter periods is 25*4 = 100.


Now we have a standard Annuity saving plan, and the formula is

    212387 = D%2A%28%28%281%2B0.08%2F4%29%5E100-1%29%2F%280.08%2F4%29%29,     (2)


where D is the quarterly deposit amount.


The multiplier  %28%281%2B0.08%2F4%29%5E100-1%29%2F%280.08%2F4%29  is equal  312.2323 ,  


which implies from equation (2)  that  D = 212387%2F312.2323 = 680.22.


It is your answer:  During 25 years the person should deposit $680.22 at the end of each quarter to his account,

                    in order to withdraw  $32000  at the beginning of each year during 10 years at given conditions.

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In this site,  there is a group of lessons associated with annuity saving plans and retirement plans.  They are

    - Ordinary Annuity saving plans and geometric progressions
    - Annuity Due saving plans and geometric progressions
    - Solved problems on Ordinary Annuity saving plans
    - Withdrawing a certain amount of money periodically from a compounded saving account
    - Miscellaneous problems on retirement plans

From these lessons,  you can learn the subject and can see many similar solved problems.