it is not representative of the whole school because you asked only peple at the gym
what if there happened to be 1 person at the gym,
therfor you conclude that 100% of people at school exercise?
rediculus
1. no, becuse yo only asked peple at gym who are probaly exercising or pretenitng to exercise or showing off
2. yes, at the doors of the school or the school cafeteria or where there is a mixed group of people, the more the better, if you can survey the entire school, great
3. that is an either or situation, also people don't like to be called a couch potato so theere will be some people who will lie and say they exercise every day and there will be some peple wo don't want to answer and there will be some who will think you are insulting them and punch you
you will have biased results since you changed the question to the extermes