Data indicate that the age of fines (i.e. number of days until paid) is normally distributed with a mean of 28 days and a standard deviation of 8 days.
a. Reminder letters will be sent to the oldest 15% of fines. How many days should a fine be outstanding before a reminder is sent?
b. The admin will give a discount to those fines paid by the 21st day. What percent will receive a discount?

Thank you for taking the time to copy your homework to AMHD.
Please refer to this announcement: https://www.askmehelpdesk.com/finance-accounting/announcement-font-color-ff0000-u-b-read-first-expectations-homework-help-board-b-u-font.html

Use z=\frac{x-{\mu}}{\sigma}