The number of 15-year old students that took part in the survey is 300 students and 20 "15-year old" students spent between 35 and 45 minutes on social media.
What is a frequency polygon?
A frequency polygon can be defined as a type of line graph that is used to plot a class frequency against the class midpoint.
For the 15-year old students, the total number of students would be calculated by adding all the data points at each frequency:
Total students = 30 + 30 + 50 + 60 + 40 + 50 + 40
Total students = 300 students.
Part B.
In order to determine the number of 15-year old students than 11-year old that spent between 35 and 45 minutes on social media, we would calculate the average and then read it from the frequency polygon.
Average = (35 + 45)/2
Average = 80/2
Average = 40.
For the 11-year old, we have:
Frequency (40) = 40
For the 15-year old, we have:
Frequency (40) = 60
Now, we can calculate the difference as follows:
Difference = 60 - 20
Difference = 20 students.
Read more on frequency polygon here: https://brainly.com/question/13443202
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