can someone help me with the formula to use with python

Question

Write a function investment(PMT, n, i) that calculates your customer's savings at some point in the future, if:

an amount is invested at the END of every year, starting with amount of PMT at the end of this year,
at an interest rate of i% per year, compounded annually,
the investment amount doubles every second year (cumulatively).

IMPORTANT:
Your function may not call any of the other functions you've defined in this project.

### START FUNCTION 7

def investment(PMT, n, i):

# YOUR CODE HERE

return round(investment_balance, 2)

### END FUNCTION 7
IMPORTANT:
Your function needs to return an float value correctly rounded to 2 decimal places.

If your answer is not rounded correctly to 2 decimal places, you will receive 0 for the question.

Make sure that the following tests all give a True result:

investment(15000, 30, 0.1045) == 1954935238.47
investment(10000, 40, 0.1045) == 41728281751.16

Answer 1

Here is a possible solution. Please check it out, if it is correct.

def investment(PMT, n, i):
investment_balance = 0.00
for k in range(1,n+1):
if k%2 == 0:
PMT = PMT*2
investment_balance = investment_balance * (1.0 + i) + PMT
return round(investment_balance, 2)

print(investment(15000.0, 30, 0.1045) == 1954935238.47)
print(investment(10000.0, 40, 0.1045) == 41728281751.16)