In a city with three high schools, all the ninth graders took a Standardized Test, with these results: High School Mean score on test # of 9th graders Glenwood. 81 268 Central City. 92 328 Lincoln High. 68 158 The city's PR manager, who never took statistics, claimed the mean score of all ninth graders in the city was 80.3 . Of course, that is incorrect. What is the mean score for all ninth graders in the city? Mean of all 9th grader's scores =