jayeshbtrivedi2006,
To get the number of students that got a lesser score, use the RANK function, and subtract 1.
For example, if you have a list of scores in B2:B7, your formula to find the number of students with lower scores than B4 would be:
=RANK(B4,B$2:B$7,1)-1
Hope this helps,
Dennis
EDIT: Ha! You guys may be faster, but my idea is... well, DIFFERENT!