Question

1. Write Python program that use a while loop to determine how long it takes for an investment to double at a given interest rate.

The input will be an annualized interest rate, and the output is the number of years it takes an investment to double.

Note: The amount of initial investment can be any positive value, you can use $1.

2. Write a function def DoubleInvest(initialInvest) to perform the same functionalities as question1. Make sure to include you main function for testing.

Answer 1

Given below is the code for question. Please indent code as shown in image.

Answer 1)
=====
initialAmt = 1
rate = float(input('Enter interest rate: '))
finalAmount = initialAmt
years = 0

while finalAmount < 2 * initialAmt:
   years = years + 1
   interest = finalAmount * rate / 100.0
   finalAmount = finalAmount + interest
  

print('At an interest rate of {:.2f}, your initial investment of ${:.2f} will be ${:.2f} in {} years'.format(rate, initialAmt, finalAmount, years))

Answer 2)
=====
def DoubleInvest(initialInvest):

   rate = float(input('Enter interest rate: '))
   finalAmount = initialInvest
   years = 0

   while finalAmount < 2 * initialInvest:
       years = years + 1
       interest = finalAmount * rate / 100.0
       finalAmount = finalAmount + interest
      

   print('At an interest rate of {:.2f}, your initial investment of ${:.2f} will be ${:.2f} in {} years'.format(rate, initialInvest, finalAmount, years))

def main():
   initialInvest = 1
   DoubleInvest(initialInvest)

if __name__ == "__main__":
   main()

output
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Enter interest rate: 5
At an interest rate of 5.00, your initial investment of $1.00 will be $2.08 in 15 years