| 
 
 
 
Question 1096173:  You want to have $6,000 saved up for a new car in 4 years. How much should you deposit each quarter into an account paying 8% compounded quarterly? 
 Answer by jim_thompson5910(35256)      (Show Source): 
You can  put this solution on YOUR website!  
We will use this formula 
FV = P*( (1+i)^n - 1 )/i 
where generally, 
FV = future value of annuity 
i = interest rate per period 
n = number of periods
 
 
Specifically we can say 
FV = target amount of money we want four years into the future 
i = interest rate per quarter 
n = number of quarters
 
 
In this case, we are given 
FV = 6000 
i = (interest rate in decimal form)/(compounding frequency) = 0.08/4 = 0.02 
n = (compounding frequency)*(number of years) = 4*4 = 16
 
 
Plug FV = 6000, i = 0.02, and n = 16 into the formula. Then solve for P
 
 
FV = P*( (1+i)^n - 1 )/i 
6000 = P*( (1+0.02)^16 - 1 )/0.02 
6000 = P*( (1.02)^16 - 1 )/0.02 
6000 = P*(1.372786 - 1 )/0.02 
6000 = P*(0.372786/0.02) 
6000 = P*18.6393 
6000 = 18.6393*P 
18.6393*P = 6000 
18.6393*P/18.6393 = 6000/18.6393 
P = 321.900501 
P = 321.91
 
 
So the answer is $321.91
 
 
I rounded up to the nearest penny so we could clear the hurdle. Notice how if P = 321.90, then we have FV equal to... 
FV = P*( (1+i)^n - 1 )/i 
FV = 321.90*( (1+0.02)^16 - 1 )/0.02 
FV = 321.90*( (1.02)^16 - 1 )/0.02 
FV = 321.90*(1.372786 - 1 )/0.02 
FV = 321.90*(0.372786/0.02) 
FV = 321.90*18.6393 
FV = 5999.99067 
FV = 5999.99 
Showing that we come up 1 cent short of our goal
 
 
On the other hand, if we have P = 321.91, then FV is... 
FV = P*( (1+i)^n - 1 )/i 
FV = 321.91*( (1+0.02)^16 - 1 )/0.02 
FV = 321.91*( (1.02)^16 - 1 )/0.02 
FV = 321.91*(1.372786 - 1 )/0.02 
FV = 321.91*(0.372786/0.02) 
FV = 321.91*18.6393 
FV = 6000.177063 
FV = 6000.18 
we haven't landed on the exact value of $6000 but overshot it (which is better than coming up short). So this confirms we have the correct answer of $321.91 
 
  | 
 
  
 
 |   
 
 |   
 |  |