To generate Jessica's demand curve for eyeglasses, we need to understand how Jessica's quantity demanded changes with the price. A demand curve typically plots price against quantity demanded, showcasing the relationship between these two variables. Here, let's break down each piece of information and see whether it is essential:
1. How many eyeglasses she buys in total: This information provides an overview of the total quantity she purchases, but it does not give us insight into how her purchasing behavior changes with different prices. Hence, this info is not sufficient by itself for generating the demand curve.
2. How many eyeglasses she buys at each price point: This is critical because a demand curve is derived by plotting the quantities demanded at various price levels. Knowing the quantity she buys at different prices ([tex]$45, $[/tex]65, $98) allows us to establish the points on the curve.
3. Whether her eyeglasses consumption goes up or down with price: This information indicates the general relationship and slope of the demand curve. It tells us whether the graph will have a downward slope (typical demand behavior) or behave otherwise. However, this by itself does not suffice as it doesn't quantify the specific quantities at different prices.
4. Whether or not she switches to a substitute when the price is high: This gives insight into her behavior regarding substitute goods and complements understanding of demand elasticity. However, just like the total quantity, it doesn't directly help us plot the demand curve for eyeglasses.
Given the above analysis, the most crucial additional information needed to generate Jessica's demand curve for eyeglasses is:
How many eyeglasses she buys at each price point.
This detailed information allows us to plot the demand curve accurately by providing specific quantities correlated with specific prices. This crucial step ensures we represent Jessica's demand relationship precisely on a graph.
