What is one difference between fixed-rate mortgages and variable-rate mortgages?
a. the borrower can adjust monthly payment depending on his budget.
b. the interest rate may change depending on the condition of the economy.
c. the lender can adjust the monthly payment dates whenever he wants to.

Asupermarket has been experiencing long lines during peak periods of the day. the problem is noticeably worse on certain days of the week, and the peak periods are sometimes different according to the day of the week. there are usually enough workers on the job to open all cash registers. the problem is knowing when to call some of the workers stocking shelves up to the front to work the checkout counters. how might decision models the supermarket? what data would be needed to develop these models?