4. why doesn't a change in the price of eggs cause a change in the demand for eggs? what causes a shortage and how can it fairly quickly be resolved?

Eggs are a necessity and the price of eggs usually wouldn't change the demand of eggs because people need eggs enough to purchase them at any price.  It's also because a price change usually occurs as a result of a demand change, not the other way around (unless they lose a lot of money).  What causes a shortage is when there isn't enough of a product produced and it depends on the item as how quickly it can be fixed.  If it's a "made" product, then the turn around can be pretty quick.  It just comes down to the company making more.  But if it's a grown or produced product, like corn, it is up to the farming industry as to how fast it can be resolved. 

The business cycle is the periodic but irregular up-and-down movement in economic activity, measured by fluctuations in real gross domestic product (gdp) and other macroeconomic variables. a business cycle is typically characterized by four phases—recession, recovery, growth, and decline—that repeat themselves over time. economists note, however, that complete business cycles vary in length. the duration of business cycles can be anywhere from about two to twelve years, with most cycles averaging six years in length. some business analysts use the business cycle model and terminology to study and explain fluctuations in business inventory and other individual elements of corporate operations. but the term "business cycle" is still primarily associated with larger (industry-wide, regional, national, or even international) business trends.