
Andrew M. answered 07/20/16
Tutor
New to Wyzant
Mathematics - Algebra a Specialty / F.I.T. Grad - B.S. w/Honors
We need to know how often the interest is compounded...
Annually, semiannually, quarterly, or monthly..
However, I will do this assuming monthly compounding just to show how.
1) The total Peter can pay is $255 per month for 4 years.
That is 48 monthly payments of $255
255(48) = $12,240 total pay off amount including interest
Compound interest formula
A = P(1+r/n)nt
A = final amount = 12240
p = initial investment (to be determined)
r = interest rate as decimal = .11
n = number of times compounded per year = 12
t = time in years = 4
12240 = p(1 + .11/12)12(4)
P = 12240/(1 + .11/12)48
P = $7898.82
He can afford to buy a car that costs $7898.82 assuming
interest is compounded monthly.
If the compound period is different just change the value of "n"
in the equation and rework.
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For interest compounded annually:
12240 = p(1+.11)4
p = 12240/(1.11)4
p = $8062.87
if interest is compounded only once per year (annually)