Question 10 of 10 Theresa has a credit card that uses the average daily balance method For the first 12 days of one of her billing cycles, her balance was 350 and for the last 19 days of the billing cycle, her balance was 520 If her credit card's APR is 14% , which of these expressions could be used to calculate the amount Theresa was charged in interest for the billing cycle? A. ((0.14)/(365)cdot 30)((12cdot 350+19cdot 520)/(30)) B ((0.14)/(365)cdot 31)((19cdot 350+12cdot 520)/(31)) C ((0.14)/(365)cdot 30)((19cdot 350+12cdot 520)/(30)) D ((0.14)/(365)cdot 31)((12cdot 350+19cdot 520)/(31))

To calculate the amount Theresa was charged in interest for the billing cycle, we need to use the average daily balance method.<br /><br />The average daily balance is calculated by taking the sum of the daily balances and dividing it by the number of days in the billing cycle.<br /><br />In this case, Theresa's balance was $350 for the first 12 days and $520 for the last 19 days.<br /><br />So, the average daily balance can be calculated as:<br /><br />Average daily balance = (12 * $350 + 19 * $520) / 31<br /><br />Now, to calculate the interest charged, we need to multiply the average daily balance by the daily interest rate and then multiply it by the number of days in the billing cycle.<br /><br />The daily interest rate is calculated by dividing the APR by 365.<br /><br />Daily interest rate = 14% / 365<br /><br />The number of days in the billing cycle is 31.<br /><br />So, the expression to calculate the interest charged can be written as:<br /><br />Interest charged = (Daily interest rate * Number of days) * Average daily balance<br /><br />Substituting the values, we get:<br /><br />Interest charged = (14% / 365 * 31) * ((12 * $350 + 19 * $520) / 31)<br /><br />Therefore, the correct expression to calculate the amount Theresa was charged in interest for the billing cycle is:<br /><br />D. $(\frac {0.14}{365}\cdot 31)(\frac {12\cdot \$ 350+19\cdot \$ 520}{31})$