Answer
a) mystery novels
b) Beethoven recordings
c) subway rides during the next five years
d) root beer
Work Step by Step
a) Mystery novels would have more elastic demand over required textbooks due to the availability of substitutes. Required textbooks do not have substitutes, however there are many mystery novels to choose from.
b) Beethoven recordings are an example of a narrower market definition. It is easier to find close substitutes for narrowly defined goods.
c) Subway rides over the next five years (a longer duration) would have more elastic demand because over a longer time horizon, people are able to change their behavior more easily. Over the short term, if the price of a subway ride increases, there may be a decrease in quantity demanded, but over time, as more people switch to driving or another alternative, the quantity demanded of subway rides would fall more substantially.
d) Root beer is not a necessity but water is. Therefore it can be easy to substitute root beer with another beverage, but water is necessary for us to survive - hence it has a more inelastic demand.
