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Question 923755:  I have been pounding my head for 2 days trying to figure out the right equation for this problem and I am hoping someone here can help.   
What is the amount a person would have to deposit today to be able to take out $5000 a year for 10 years from an account earning 8 percent annually?  
Thanks! 
 Found 2 solutions by  josgarithmetic, KMST: Answer by josgarithmetic(39630)      (Show Source): 
You can  put this solution on YOUR website! p, amount to deposit today.
 
 
YEAR_________________BAL 
0___________________p(1.08)^0 
1___________________p(1.08)^1 
2___________________p(1.08)^2 
y___________________p(1.08)^y
 
 
Your question asks,   to find p. 
 Answer by KMST(5328)      (Show Source): 
You can  put this solution on YOUR website! The way I understand it you want to know how much money should be deposited at time = 0 years, 
into an account earning 8 percent annually, 
so that at t=1 year, t=2 years, ..., t=8 years, 
there would be at least $5000 that can be taken out. 
At   ,   . 
At   (at the end of the first year) 8% interest (   is added to the balance, 
bringing the balance up to   , 
and immediately,   is taken out, 
bringing the balance down to   
At   ,   is again 
increased by a factor of   , 
and reduced by the withdrawal of   , so 
  . 
At   ,   is again 
increased by a factor of   , 
and reduced by the withdrawal of   , so 
  . 
This pattern repeats every year, and 
at   , 
  
If at that point   , 
  
  
  
  
  
  
NOTE: 
The sum   
is the sum of a geometric sequence with ratio   . 
You may know a formula for that, but otherwise you can see that 
  , and then 
 ---> --->  
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