Hello!
According to the exercise, each boy in the graph corresponds to 100 students.
Considering it, let's solve your exercise:
(a) How many students are at Greyhawk Middle School?
Well, there are 4 boys in the graph. It means that it is:
[tex]4\times100=400\text{ students}[/tex]
(b) How many more students are at Madison Middle School than at Hillside Middle School?
Madison Middle School: 6 x 100 = 600 students
Hillside Middle School: 5 x 100 = 500 students
So, subtracting:
Madison - Hillside = 600 - 500 = 100 students.
Answers:
(a) 400 students.
(b) 100 students.