When all workers who want jobs have them and the demand for and supply of labor are in equilibrium, a. the unemployment rate will be zero. b. the economy will be experiencing high rates of inflation. c. unemployment is at its natural rate. d. frictional unemployment will be zero.

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?