In order to study the length of time after billing for customers to settle the payments a manager of a virtual bank took

[answerhappygod]

In order to study the length of time after billing for customers
to settle the payments a manager of a virtual bank took a random
sample of 100 credit card invoices A frequency table tor the
data on payment time. i.e.. the number of days between the
invoice date and the payment receipt date, was constructed as
below:
In order to encourage early payment, the following scheme is
introduced:
- For payments made before the mean payment time. the company
refunds the customers for each invoice $50 a day for the number of
days before the mean payment time.
- For payments made after the mean payment time, the
company charges the customers for each invoice $100 a day for the
number of days after the mean payment time
How much on average will the bank receive/spend per invoice on
the above 100 invoices under this scheme?