Many people misunderstand what these scores mean. The 3-digit score does NOT mean the number of questions. (The USMLE does not publish percentile information.)
Understand that 3-digit scale is invented scoring scale intended to obscure information like how many questions the student got correct in USMLE exam. All the student will really know when they see their results is that higher is better and lower is worse.
To have a reasonable chance at getting a residency position, student should try to score about 220 on the 3-digit scale. If they fall short of this mark, they can still get a residency position, but it will be harder.
Note that the USMLE examination is not scored “on a curve”. Students are not scored against each other, but relative to a per-set annual standard. This standard is constant for the year. Both US medical students and IMGs are scored using the same standard.