More and more people are paying with credit cards. a study conducted in 1995 reported that 18% of the respondents paid for a specific type of purchases with plastic, whereas a similar study in 2005 indicated that 25% paid for specific type of purchase with plastic(no sample sizes were reported for either study). Suppose that a new survey taken in 2007 indicated that 31% paid for a specific type of purchase with plastic. suppose that all three studies used a sample size of 500.
a) Is there evidence of a siginificant difference among the three years in the proportion of respondents who paid for a specific type of purchase with plastic?
b) determine the p-value in (a) and interpret its meaning
c) if appropriate use the maracuilio procedure and alft=0.05 to determine which years are different.