how many hours should xth students study to get above 90%?

I think it just depends on how well do you study and how well do you understand the information. You can't tell how long.. It all depends on the person and how he or she understands the information.

Well i think it's not reasonable to give a one size fits all sort of approach to studying. I might have needed 3 - 4 hours just for my math courses in college and an hour for my multimedia classes... does that mean that is what YOU should do? Nope. Each person knows their strengths and weaknesses and in which subjects. However, suffice it to say that a minimum of 30 minutes per subject without any assignments for a subject is the bare minimum. For you, with such a high goal... depending on which subjects you have difficulty with... 5 -6 hours is a goal to try to reach. Try using resources at your school such as tutors. Ask lots of questions... that's why the teachers are there.. (nothing more frustrating than asking do you understand and a blank nod comes my way)

Well id like to start off bby saying that everyone learns a differnet paces and it may take some people longer to get to where they need to be to get 90 percent o higher. In highschool,to which im assuming your asking about (as a 90 percent average in university is insanity), I was around this range for most of my later years. For me it took a good three hours of reading the text books over making notes and letting all the information seep in. However i needed to do example after example to get those math, chem and physics questions down. I would suggest that you see whats right for you and go from there, a 90 average is not an easy thing to obtain so i would expect it to take up a considerable amount fo time no matter who you are.

Normally 4-5 hrs of focused study is enough for getting good marks in Exam. It really depends upon the individual how he or she can cope with the studies. But what matters is the student's concentration while studying. One should also indulge in some play work as that helps to clear some tension. If you ask most of the students who score above 90% they not only study hard but also find time to find some leisure time. The key is time- management.