Question 11 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 75 286 Central City 92 335 Lincoln High 69 185 The city's PR manager, who never took statistics, claimed the mean score of all ninth graders in the city was 78.7 . Of course, that is incorrect. What is the mean score for all ninth graders in the city? Mean of all ninth grader's scores = Round to 2 places