Exam

Hey,
I am one of the best examples that you can relate to.
I've done my BDS and worked in a clinic for an year. Then gave my CAT, XAT, SNAP etc, and scored a whooping 97.36 percentile. I am currently an alumnus of XIMB-HR working in Jodhpur.
I also had a dentist amongst my seniors and one among my juniors in PG. A junior dentist gave her CAT and scored 99.2 and is an alumnus of IIM Calcutta. She didn't like being a dentist too.
Campus placements are good if you are good with your presentation skills, communication and are diligent enough. If you have a love for it, broaden your horizons, you need not stick to MHA nor think that you have wasted 5 years. It, infact, is a unique factor and helps you to get noticed.
As for me, I've never regretted choosing this path because just like you, I've always dreamed of being associated with big companies. Following your passion might not be always possible but doing what you dont like is something you might have to live with regretting for the rest of your life. Choose well.
All the best!!
Edit: An year after my MBA, I have now moved to my home state, working with Accenture. Your hardwork will pay.

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Graduation from an accredited college or university with a satisfactory academic record. Submission of an official score report for the Graduate Record Examination GRE General Test taken within the last five years. The GRE requirement is waived for applicants who have completed a Masters degree from a regionally accredited college or university in the United States. Three letters of recommendation. The mission of the Computer Science programme at FDUs Florham Campus is to engage in education, research and service activities required for creating the knowledge of Computer Science which has become essential in our global technological society.

No, without taking an entrance exam, you might not be eligible for admission to the University College of Medical Sciences.
The University College of Medical Sciences is affiliated with Delhi University and is recognized by the Medical Council of India (MCI).
Accordingly, you will be required to give some kind of national-level entrance exam to get admission into this college. For instance, you would be required to give NEET for MBBS, NEET-PG for MD and MS, and NEMT for MS courses.
Similarly, you will need to give the college entrance exams for some other courses like the B.Sc. in Medical Technology (Radiography) and M.Sc. in Medical Imaging Technology (Radiography) courses.
In addition, you will be required to fulfill a basic eligibility criterion.
Like for BSc, you should have passed 12th grade with a minimum of 60% marks in the science stream, and for MSc, you must have passed a bachelor's degree in sciences in medical technology (radiography) and medicine from any recognized university.