how to calculate pass mark if 60% of students pass

Question

Estimating the pass mark if out of 100 students 60% passed

Answer 1

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.