In a city with three high schools, all the ninth graders took a Standardized Test, with these results: High School Mean score on test Number of ninth graders Glenwood 79 258 Central City 96 318 Lincoln High 73 184 The city's PR manager, who never took statistics, claimed the mean score of all ninth graders in the city was 82.7 . Of course, that is incorrect. What is the mean score for all ninth graders in the city? Round to one decimal place. mean of all ninth grader's scores =