Question

in a city with three high schools, all the ninth graders took a standardized test, with these results:
high school | mean test score | number of ninth graders (frequency)
glenwood | 84 | 275
central | 93 | 302
lincoln | 73 | 160
the citys pr manager, who never took statistics, claimed the mean score of all ninth graders in the city was the average of 84, 93, and 73, which is 83.3. 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 graders scores =
hint: textbook measures of center

Explanation:

Step1: Calculate total score for each school

For Glenwood: $84\times275 = 23100$
For Central: $93\times302 = 28086$
For Lincoln: $73\times160 = 11680$

Step2: Calculate total number of students

Total students = $275 + 302 + 160 = 737$

Step3: Calculate total score of all students

Total score = $23100 + 28086 + 11680 = 62866$

Step4: Calculate the mean score

Mean = $\frac{62866}{737} \approx 85.3$

Answer:

85.3