In each of the following situations, indicate the statistical analysis you would conduct and the appropriate test or test statistic that should be used.

a. Consumer preferences for Coca-Cola were obtained on an 11-point Likert scale. The same consumers were then shown a commercial about Coca-Cola. After thecommercial, preferences for Coca-Cola were measured again. Has the commercial been successful in inducing a change in preferences?

b. Respondents in a survey of 1,000 households were asked to indicate their frequency of domestic air travel on an interval scale. They were also classified as being in high- or low-income categories. Is the frequency of domestic air travel related to income level?

c. In a telephone survey using a representative sample of 3,000 households, the respondents were asked to indicate their preference for fast-food restaurants using a 7-point Likert scale. The sample was divided into small and large households based on the number of people in the household. Does preference for fast-food restaurants vary by household size?