Question

Hi! I'm stuck on the third problem of PS1. I've gotten to where the code returns answers, but they don't match the answers given in the assignment PDF. Does anyone have suggestions?

b=float(raw_input('What is your balance? '))
i-float(raw_input('What is your interest rate?'))
p=0.01
balance=b
low=b/12.0
high=(b*(1+(i/12.0))**12.0)/12.0
while True:
for month in range (1,13):
balance=balance-guess
balance=balance+((i/12,0)*balance)
if balance>0 and balance>-p:
low=guess
balance=b
elif balance<0 and balance>-p:
high=guess
balance=b

Answer 1

(sorry, got cut off)
else:
print ('Result:')
print ('Lowest payment possible: ' + str(round(guess,2)))
break

Answer 2

if p is your margin of error due to floating point imprecision your condition should be
if balance < p and balance > -p:
##code
or more succinctly:
if abs(balance) < p:
##code

the way you wrote your first condition is redundant:
" if balance>0 and balance>-p:"
if balance is greater than 0, it must also be greater than -p.
I would also recommend making your margin of error smaller than what you eventually round to, i.e. p=1e-6 would be more precise

Answer 3

So right now I have
for month in range(1,13):
balance=balance-guess
balance=balance+((i/12.0)*balance)
if balance>0:
low=guess
balance=b
elif balance<p and balance>-p:
high=guess
balance=b
else:
print('Lowest payment: ' + str(round(guess,2)))
break

I'm still not sure how to fix it.