Question

Prob1c,

RemainingBalance = (RemainingBalance*(1 + MonthlyRate)) - Payment

Gives me 26956.44 for a monthly payment, but test case in handout shows 29643.05

Answer 1

please show your whole code

Answer 2

## a credit card program that calculates the minimum fixed monthly payment needed in order to pay off a credit card balance within 12 months.
## this more complicated version uses a bisection search method and upper and lower bounds

InitialBalance = float(raw_input('What is the outstanding balance?'))
apr = float(raw_input('What is the annual interest rate?'))

MonthlyRate = apr/12.0
PaymentLow = InitialBalance/12.0
PaymentHigh = (InitialBalance * (1 + MonthlyRate)**12.0)/12.0
Payment = (PaymentLow + PaymentHigh)/2.0
RemainingBalance = InitialBalance

while ((RemainingBalance > 0.010) or (RemainingBalance < -0.010)):


RemainingBalance = InitialBalance

for i in range(12):
RemainingBalance = (RemainingBalance*(1 + MonthlyRate)) - Payment

if RemainingBalance > 0.010:
PaymentLow = Payment
Payment = (Payment + PaymentHigh)/2.0
if RemainingBalance < -0.010:
PaymentHigh = Payment
Payment = (Payment + PaymentLow)/2.0

print ('Monthly payment to pay off debt in 1 year: ' + str(round(Payment,2)))
print ('Balance: ' + str(round(RemainingBalance,2)))

Answer 3

your formula to update the balance is wrong:
RemainingBalance = (RemainingBalance*(1 + MonthlyRate)) - Payment

payment needs to be subtracted before multiplication by 1+MonthlyRate

Answer 4

I don't think that's correct. If you look at the handout ( http://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-00sc-introduction-to-computer-science-and-programming-spring-2011/unit-1/lecture-4-machine-interpretation-of-a-program/MIT6_00SCS11_ps1.pdf)
I'm using the same formula.

Answer 5

that link is not working for me, but I did the same problem once on OCW and once for edX so I think mine is right
did you try it to see if you get the right answer

Answer 6

?

Answer 7

No it doesn't give the correct answer and it doesn't jive with interest payments. The interest accrues and then you pay off the interest plus a portion of the principle. I also checked my answer in excel and it is correct.

Answer 8

what are the inputs for balance and interest that you are trying to get the answer 29643.05 from?

Answer 9

Ah that's it, I was entering in .02 instead of .2 -- I did the program right.
Thanks!

Answer 10

congrads lol