i didnt understand the concept of proportion i mean what would that proportion column look like if pass or fail is a boolean ?
proportion of pass students here is a population parameter and it will have ONE VALUE only for entire population.
In this particular example:
proportion = \frac{Number\ of\ students\ passing\ the\ examination}{Total\ number\ of\ students}
Note that for calculating number of students passing the examination, you can simply add 1's and 0's assigned to each student.