So far we have read in the forum various views on this subject, some predicted 15 some predicted 10 as the standard deviation in order to find the total number of student passing the test and the tentative ranking order based on scores of each student.

I was trying to find out which SD looks more probable.

We only have information that 110 is the pass mark this year and maximum score is 130.12.

What I gathered from reading some old post in other forums that usually the pass mark is kept such that around 30% of the cohort pass the test.

If we use Standard Deviation of 15 then NORMDIST(110,100,15,TRUE)*100 yields that 74.75% of total 1203 cohort this year (i.e 304 students) might have got above 110 pass marks. But this also gives 27 students above 130.12 score which we know is not true.

If we use Standard Deviation of 10 then NORMDIST(110,100,10,TRUE)*100 yields that 84.1% of total 1203 cohort this year (i.e 191 students) might have got above 110 pass marks. This now gives 2 students above 130.12 score which though looks more probable but only 84% of cohort passing the test is a bit too low I think .

Whereas if we use Standard Deviation of 12.5 then NORMDIST(110,100,12.5,TRUE)*100 yields that 78.8% of total 1203 cohort this year (i.e 255 students) might have got above 110 pass marks. This gives only 3 students above 130.12 score and 1 student above 141 (which then fits the usual calculator of maximum 141 achieved).

I am quite new to this forum and am just trying to figure out things from other region's forum.

Any expert comment welcome as we all are trying to guess where our DSs stand in the ranking order for Reading Boys.