Final answer:
The demand for a good does not necessarily change when the price of that good changes if other influences on buying plans remain constant.
Step-by-step explanation:
The demand for a good, such as gym memberships, does not change when the price of that good changes with no change in other influences on buying plans. This is because the price of a good is only one factor that affects demand. Other factors such as the population, the expected future price of the good, and the price of complementary goods can also influence demand.
For example, if the price of a gym membership increases, the demand for gym memberships may not change if there is no change in the population, the expected future price, or the price of complementary goods like bottled water. In this case, people may still value the benefits of a gym membership and be willing to pay the higher price.
Therefore, when analyzing changes in demand, it is important to consider all the factors that can affect buying plans and not just the price of the good.