The file BadDebt.xls contains a record of sales invoices that your firm sent out last year, including the date the invoice was sent (billing date), the dollar-amount of the invoice, and the date on which payment was submitted. Some invoices are marked as "Not Paid". Those invoices were still unpaid after one year, at which time the firm classified them as uncollectable Bad Debt. Using the data, we want to estimate the probability that an invoice will end up as Not Paid ("Bad Debt"), given that the invoice has already gone a certain length of time without being paid. A standard way to do this is to group invoices into age-based categories. The firm's payment terms are "net 31" meaning that any payment made within 31 days is considered on time: Category ] days to receive payment Description On time 1-31 paid on time Paid 1-60 past due 32-91 payment late, no penalty Paid 61-90 past due 92-121 payment late, late fee charged Paid over 90 past due 122-366 payment late, late fee increases Bad debt n/a not paid For example, the first invoice in the data set was paid in 6 days, and was therefore paid while in the