The number of students in the marching band is 600 / 5 = <<600/5=120>>120 students
The number of students that play a brass instrument is 120 / 2 = <<120/2=60>>60 students
The number of students that play the saxophone is 60 / 5 = <<60/5=12>>12 students
The number of students that play the alto saxophone is 12 / 3 = <<12/3=4>>4 students
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