If 60% of 100 students passed, then 60 students passed.
Let's say the pass mark was 45%, then it means that 60 students scored 45% or more.
If the pass mark was 67%, then 60 students scored 67% or more.
The number of students obtaining a pass is not directly related to the pass mark. The probability that a student selected randomly obtained a pass is 60%, but it doesn't determine the pass mark itself.