For purposes of illustration, In the state of Tamil Nadu, the government holds a Tamil Nadu Professional Courses Entrance Exam (TNPCEE) to determine entry to engineering colleges in the state. A "cutoff mark" refers to the score of the last applicant admitted to a particular engineering college. The cutoff score varies for different engineering colleges and for different courses in each engineering college. It also varies for different categories of students based on the government's reservation policies to set aside seats for certain communities.
The Tamil Nadu government calculates each student's eligibility for admission using a combination of her score on the TNPCEE, as well as her performance on the 12th grade government examinations. The TNPCEE exam performance earns 100 points, and the student's performance in math, physics and chemistry earns another 200 marks combined. Of this, the math score accounts for 100 points, while the physics and chemistry scores account for 50 points each. The government then ranks the students based on how much they score out of the total of 300 points.
There are many engineering colleges in India, with some being better established and better regarded than others. The way the system works is that students with higher scores on the scoring system will have a greater chance of getting into these sought after institutions, such as Anna University. And those who score lower will have less of a chance of getting into their college of choice. This means that the cutoff marks tend to be higher for the higher-ranked colleges.
Not only is there a ranking by college, but students also have preferences for certain branches of engineering. Thus, those who score higher have better chances of getting into the study areas that are most sought after, such as computer engineering and electronics and communication engineering. The less sought after the course, the higher the chances of a low scoring person getting in. In this sort of hierarchy, the highest scoring persons have optimized their chances of getting into the most sought after courses at the best ranked universities.