Annual income of older adults. In the study described in the previous exercise, 1434 subjects out of a total of 2533 reported that their annual income was $25,000 or more.
(a) Give a 95% confidence interval for the true proportion of subjects in this population with incomes of at least $25,000.
(b) Do you think that some respondents might not give truthful answers to a question about their income? Discuss the possible effects on your estimate and confidence interval.
(c) In the previous exercise, the question analyzed concerned pet ownership. Compare this question with the income question with respect to the possibility that the respondents were not truthful.