"Block's sells 500 bottles of perfume a month when the price is $7. A huge increase in resource costs causes price to rise to $9 and Block's only manages to sell 460 bottles of perfume. The price elasticity of demand is:"

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?