It is a data set that can be shown as its mean after totals are multiplied. It can also be part of a question set of discrete data where all data is totaled up and further info shown to find a mean of each school. To find such mean it uses the third set of data to replace the 2nd data (students 1-25) replacing with no of students (with reference to lining up with the first list being list one hours 1, 2,3,4,5 etc. Here when say larger data says 250 students in the borough spend 1 hr we can multiple these factors to get the first multiplication value to multiply that with the totals added under each title. So it would read h x s x h(s) to find such discrete mean.
