申请round 3成功的可能性是否比较小?

如果是４round的business school (不包括early decision)，　申请round 2与round 3会相差很多吗。

essay实在赶不上时间了，　还有不到３天

Depending on your background.  The number of admitted applicants in R3 is significantlly lower than R1 or R2.  You might be better off applying for R1 at the end of this year.  Good luck!