30. a businessweek/harris survey asked senior executives at large corporations their opinions about the economic outlook for the future. one question was, "do you think that there will be an increase in the number of full-time employees at your company over the next 12 months? " in the current survey, 220 of 400 executives answered yes, while in a previous year survey, 192 of 400 executives had answered yes. provide a 95% confidence interval estimate for the difference between the proportions at the two points in time. what is your interpretation of the interval estimate? anderson, david r.. essentials of statistics for business and economics (p. 472). south-western college pub. kindle edition.