Question

Atthebeginningofa31-daybillingperiod,Sandrahasanunpaidbalanceof$720onhercreditcard.Threedaysbeforetheendofthebillingperiod,shepays$400.Findherfinancechargeat2.1%permonthusingtheaveragedailybalancemethod.

Answer 1

uhh kk thx for that but it makes no sense at all.

Answer 2

We need to calculate the average balance per day.

In this case, the billing period has 31 days and Sandras has an unpaid balance of $720 during 28 days and unpaid balance of $720-$400=$320 during 3 days, so the average balance is:

$\text{average balance=}\frac{(720\cdot28+320\cdot3)}{31}=\frac{21120}{31}=681.29$