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 82 255
Central City 92 320
Lincoln High 67 157
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? Round to one decimal place.

mean of all ninth grader's scores