BU ED2 Concern. Can anyone help figure out?

I am a student from London and I have applied ED2 to BU. Reading an article from what says to be the 'The independent student newspaper at Boston University', it says this:

"The university has sent letters of acceptance to 916 students in December, resulting in a 42 percent acceptance rate for those who applied for the first of two Early Decision rounds. Another 2,039 prospective students applied for the second round of Early Decision, and they will receive their decisions from BU by mid-February. By the end of the second round, the university plans to enroll 1,190 students in total, making up about 35 percent of the class of 2021, according to Walter."

My concern is that in the first round of early decision 916 students were accepted out of 2142 applications (it mentioned this earlier), and if they plan to accept a total of 1190 students from the early decision 2 category in total, that means that they will only give 274 people a spot at the university. How is this possible? I know that these figures may not be to the exact applicant, but I thought that it is more likely to get accepted through early decision. How is it that with similar numbers of applications, in one category they can accept 916 students and another only 274? I am now slightly worried about my chances...