In march 2015, the public policy institute of california (ppic) surveyed 7,525 likely voters living in california. in the survey, respondents were asked about global warming. ppic results show that 47% of adults age 55 and older view global warming as a serious problem, and 65% of adults age 18 to 34 view global warming as a serious problem. ppic researchers are interested in the difference in proportions of adults age 55 and over and adults age 18 to 34. the standard error for the difference in proportions is 0.011.which of the following is the margin of error for a 95% confidence interval? a) 0.011b) 0.018c) 0.021d) 0.028