if srilanka wins by a huge margin and plans to knock out Bangladesh, and India wins against Sri Lanka, then Sri Lanka will go into the Super 8 with 0 points and India with 2 points.
So the way Sri Lanka can take 2 points is by letting Bangladesh get into the Super 8. So If Sri Lanka just beat Bangladesh, then Bangladesh has a chance to go to the super 8 by beating bermuda big. Sri Lanka already has NRR 4.5, India has just 2.5. So in that case, India will have to win and win big, to have their NRR be higher than Sri Lanka. Otherwise, Sri Lanka will go in with 2 points. That is what they will want.