Answer : The north middle school have fewer than 750 students.
Explanation:
Let the number of students in south middle school be, x
and the number of students in north middle school be, y
Given:
Number students in south middle school = x = 750
and,
North middle school has 13/15 times as many students as South. That means,
........(1)
Now put the value of 'x' in expression 1, we get:


Thus, number of students in north middle school = y = 650
From this we conclude that north middle school have fewer than 750 students.
Hence, the north middle school have fewer than 750 students.