Need quey help urgent

Hi,
I have one table student, i.e stdnt_id,stdnt_name,stdnt_activity
i have values in student table like this.
stdnt_id       stdnt_name        stdnt_activity
1              kiran             5
1              kiran             10
1              kiran             15
2              sachin            5
2              sachin            10
3              venkat            5
3              venkat            10
3              venkat            15
4              kumar             5
4              kumar             10
5              naveen            5
5              naveen            10


Here stdnt_activity 5 mean -> Pending , 10 -> Inprogress, 15 means -> Closed


So, i want a query to dispaly the values of student table based on cndition.
the condition is for example:


The student kiran having stdnt_activity 5,10,15 where as sachin having stdnt_activity 5,10.


I need a query do diaplay all student records in a table which is having stdnt_activity 5,10 and not 15.


If student have stdnt_activity 5,10,15...we don't need to display to the user .


if student have stdnt_activity 5,10 then we need to display the values.




By above example i only need to diaplay the values of sachin,kumar, naveen (these student's doen's have 15).


while students kiran,venkat will have 5,10,15 ..so these records need to be ignored(no need to diaplay).