In a paragraph that is almost a direct answer to this on the MIT website:
“ MIT admissions counselors are trained to understand the educational system in your part of the world. We do not try to convert your grades to the American system, or to find other sorts of equivalence. You will not be competing against your classmates or students in other parts of the world; we do not have caps or quotas for countries. We consider each student as an individual as they proceed through our process.”