6.00.1x - ps2.py

# part 1

tp = 0 #total paid
ub = balance # updated balance
for i in range(1, 13):
  print("Month: " + str(i))
  mmp = ub * monthlyPaymentRate
  tp += mmp
  up = ub-mmp
  ub = up*(1+annualInterestRate/12)
  print("Minimum monthly payment: " + str(round(mmp,2)))
  print("Remaining balance: " + str(round(ub, 2)))

print("Total paid: " + str(round(tp, 2)))
print("Remaining balance: " + str(round(ub, 2)))

# part 2

mir = annualInterestRate/12 # monthly interest rate
mp = 10 # monthly payment
ub = balance
while ub>0:
	ub = balance
	for i in range(1, 13):
		mub = ub - mp
		ub = mub* (1+mir)
	mp+=10

print ("Lowest Payment: " + str(mp-10))

# part 3

mir = annualInterestRate/12 # monthly interest rate
mplb = balance/12
mpub = (balance*(1+mir)**12)/12

def yb(mir, ub, mp): # balance after a year
	for i in range(1, 13):
		mub = ub - mp
		ub = mub* (1+mir)
	return ub

ub = balance
for i in range(100):
	mid = (mplb + mpub)/2
	if yb(mir, ub, mid)>0:
		mplb = mid
	else:
		mpub = mid

print("Lowest Payment: " + str(round(mid, 2)))