Instructions

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

• 0.5% for a non-negative balance less than 1000 dollars.
• 1.621% for a positive balance greater than or equal to 1000 dollars and less than 5000 dollars.
• 2.475% for a positive balance greater than or equal to 5000 dollars.
• 3.213% for a negative balance (results in negative interest).

You have three tasks, each of which will deal with the balance and its interest rate.

1. Calculate the interest rate

Implement the SavingsAccount.interest_rate method to calculate the interest rate based on the specified balance:

Note that the value returned is an instance of Float.

2. Calculate the annual balance update

Implement the SavingsAccount.annual_balance_update method to calculate the annual balance update, taking into account the interest rate:

Note that the value returned is an instance of Float.

3. Calculate the years before reaching the desired balance

Implement the SavingsAccount.years_before_desired_balance method to calculate the minimum number of years required to reach the desired balance:

Note that the value returned is an instance of Integer.