How many hours required for hard work of college study -bachelor engineering BE for getting good marks?MINIMUM?

This is a silly question- some people are brilliant with science and math and would not need to study much, while other need to study a lot. Engineering is a tough curriculum so I would say about 6+ hours per day not including classes/lectures/lab and SI ( supplemental instruction)

Definitely depends on how smart you are. I knew some guys that didn't go to class and just studied for a few hours the night before tests and got really good grades, others would go to every class, every study session and study for hours every day and barely pass, so it just depends on the person.

You need 5 hrs of study, 3 hrs in the morning 2 hrs in evening total 5 hrs,early riser have advantage.Admiral V K Singh

Take 24 hours. Subtract the time spent in class. Then subtract 8 or 9 hours for sleeping, meals and hygiene. What is left if your study time.