According to the Federal Reserve Bank of Boston, among individuals who had credit cards in 2014, the mean number of cards was 3.5. Treat the individuals who have credit cards in the SullivanStatsSurveyI as a random sample of credit card holders. Go to www.pearsonhighered.com/ Sullivan stats to obtain the data file SullivanStatsSurveyI using the file format of your choice for the version of the text you are using. The results of the survey are under the column "Number of cards."

(a) What is the variable of interest in this study? Is it qualitative or quantitative?

(b) Do the results of the survey imply that the mean number of cards per individual is less than 3.5? Use the α = 0.05 level of significance.