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Interest is Interesting
Interest is Interesting

Interest is Interesting

Learning Exercise

While completing Interest is Interesting, you'll learn 1 concept

Instructions

In this exercise you'll be working with savings accounts. Each year, the balance of your savings account is updated based on its interest rate. The interest rate your bank gives you depends on the amount of money in your account (its balance):

  • -3.213% for a negative balance.
  • 0.5% for a positive balance less than 1000 dollars.
  • 1.621% for a positive balance greater or equal than 1000 dollars and less than 5000 dollars.
  • 2.475% for a positive balance greater or equal than 5000 dollars.

You have four tasks, each of which will deal your balance and its interest rate.

1. Calculate the interest rate

Implement the InterestRate() function to calculate the interest rate based on the specified balance:

InterestRate(200.75)
// Output: 0.5

Note that the value returned is a float32.

2. Calculate the interest

Implement the Interest() function to calculate the interest based on the specified balance:

Interest(200.75)
// Output: 9.0375

Note that the value returned is a float64.

3. Calculate the annual balance update

Implement the AnnualBalanceUpdate() function to calculate the annual balance update, taking into account the interest rate:

AnnualBalanceUpdate(200.75)
// Output: 201.75375

Note that the value returned is a float64.

4. Calculate the years before reaching the desired balance

Implement the YearsBeforeDesiredBalance() function to calculate the minimum number of years required to reach the desired balance, taking into account that each year, interest is added to the balance. This means that the balance after one year is: start balance + interest for start balance. The balance after the second year is: balance after one year + interest for balance after one year. And so on, until the current year's balance is greater than or equal to the target balance.

balance := 200.75
targetBalance := 214.88
YearsBeforeDesiredBalance(balance, targetBalance)
// Output: 14

Note that the value returned is an int.

Last updated 15 October 2021
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