Final answer:
The existence of substitutes affects the price elasticity of demand by making it more elastic. Consumers have the option to choose alternative products instead of paying higher prices, leading to a larger change in the quantity demanded. The availability of substitutes influences how responsive consumers are to changes in price.
Step-by-step explanation:
The existence of substitutes affects the price elasticity of demand. When there are close substitutes available for a product, the demand becomes more elastic. This means that consumers have the option to choose an alternative product instead of paying a higher price. As a result, a small price change can lead to a larger change in the quantity demanded.
For example, if the price of brand A soda increases, consumers may choose to buy brand B soda instead, as they are close substitutes. This shift in demand from brand A to brand B shows the price elasticity of demand for soda. Therefore, the availability of substitutes influences how responsive consumers are to changes in price.