Answer:
The answer is: necessity versus a luxury in determining the price elasticity of demand
Explanation:
The price elasticity of demand measures the change in the quantity demanded of a product in relation to a change in its price.
The formula for determining the price elasticity of demand (PED) is:
PED = % of the change in Quantity Demanded / % of the change in price
Usually goods or services considered luxurious (e.g. gourmet cheese), tend to be very elastic (high PED). While products considered basic necessities (e.g. gasoline, or Diet Coke in Jane´s case) tend to be very inelastic (low PED).
For example, if the price of gourmet cheese (luxury product) rises 10% and the quantity demanded drops 25%, we can say gourmet cheese is a very elastic product (PED = 2.5)
Instead, if the price of gasoline rises 10% and the quantity demanded only drops 1%, we can say gasoline is very inelastic (PED = 0.1).