Sally consumes only two goods, shoes and "everything else." For five different shopping trips (each with different prices), the prices and Sally's marginal utilities are shown below.

a. Is Sally maximizing her total utility on each shopping trip? Explain why or why not.
b. Using what you have learned in this chaptet about marginal utility, explain how the number of shoes consumed is changing as their price changes.
c. Can you detect the shape of Sally's demand curve for shoes from the data shown in the table?