Read this article: https://www.capitalone.com/learn-grow/money-management/how-to-calculate-apr-on-credit-card/. Now suppose the sum of your daily balances for last month is $2,500 and the number of days in the billing cycle is 30. Also assume the APR for your credit card is 21.40%, the average APR for US credit cards.
a) What would be your monthly interest payment?
b) If you do not make any payment at all, what would be the amount due in one year (assume there are no late fee penalties for missed payments)?