Given below is the cut off for top 20 percentile out of 500 marks for various categories for the Maharashtra board.
As you have scored 487 out of 650 you need to calculate your marks out of 500 details the rule given below-
For the top 20 percentile you have to consider the marks scored in five subjects - (1) Physics, (2) Chemistry, (3) Mathematics, (4) A language and (5) Any subject other than the above four.
If your score out of 500 us more than the ones given below according to your category, then you fall under the top 20 percentile.
Best of luck!