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 gradersGlenwood 78 269Central City 93 321Lincoln High 66 161The city's PR manager, who never took statistics, claimed the mean score of all ninth graders in the city was 79 . Of course, that is incorrect.

a. What is the mean score for all ninth graders in the city? Round to two decimal places.

We find the weighed mean to find the mean of all ninth graders in the city, that is, we multiply the mean for each high schools by the number of students in the high school, add them, and then divide by the total number of students. So

[tex]M = \frac{78*269 + 93*321 + 66*121}{269 + 321 + 121} = 82.73[/tex]

The mean score for all ninth graders in the city is 82.73.

aksnkj aksnkj · Answer 2 · 2021-11-16T11:04:41+01:00

The correct mean score of all ninth graders of the city is 81.84 marks and not 79.

Given information:

The city has three schools: Glenwood, Central city, and Lincoln high.

The score of three schools is:

Glenwood's score [tex]78 \times 269[/tex]

Central city's score [tex]93 \times321[/tex]

Lincoln high's score [tex]66 \times161[/tex]

So, the mean score of the city can be calculated as,

[tex]\bar{x}=\dfrac{78 \times 269+93 \times321+66 \times161}{269+321+161}\\=81.84[/tex]

Therefore, the correct mean score of all ninth graders of the city is 81.84 marks and not 79.

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https://brainly.com/question/23562402