Given Principal : $11,000, 128, 240 days Partial payments: On 100th day, $4,600 on 180th day, $2,800 a. Use the U.S. Rule to solve for total interest cost. (Use 360 days a year. Do not round intermediate calculations. Round your answer to the nearest cent. Total interest cost b. Use the U.S. Rule to solve for principal balances. (Use 360 days a year. Do not round intermediate calculations. Round your answers to the nearest cent.) On 100th day On 180th day Balance after the payment Given Principal : $11,000, 128, 240 days Partial payments: On 100th day, $4,600 on 180th day, $2,800 a. Use the U.S. Rule to solve for total interest cost. (Use 360 days a year. Do not round intermediate calculations. Round your answer to the nearest cent. Total interest cost b. Use the U.S. Rule to solve for principal balances. (Use 360 days a year. Do not round intermediate calculations. Round your answers to the nearest cent.) On 100th day On 180th day Balance after the payment