There are no census like this or any kind of data published by the competent authority regarding the marks vs student density. So telling about this is impossible. Although if you have your percentile then you can work out how many students have scored less than 304.

If you can get the percentile of the marks 305 then you can estimate the number of students who got 304 by substracting the percentile and the percentile you will get find the percentage of the student from the total number of students appeared. So from that you can estimate how many people had got 304 approximately. Although this can cause statistical error and the value will surely not be accurate but you will get a estimate.

I hope my answer helps you. All the very best for your future endeavors!