Then the total amount that needs to be repaid is ...
Principal + Interest = $3600 +384 = $3,984
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The time period is 16 months, so is 16/12 years.
The time periods of the interest rate and "t" in the formula must match. If the interest rate is an annual rate, then "t" is in years. If the interest rate is a monthly rate, then "t" is the number of months.