I have an issue and NO it is not homework, it's just a programmer who has been away from SQL for a long time having to solve a problem.

I have the following table:

create table students(
    studentid int identity(1,1), 
    [name] varchar(200), 
    [group] varchar(10), 
    grade numeric(9,2) 
)
go

The group is something arbitrary, assume it's the following "Group A", "Group B"... and so on.

The grade is on a scale of 0 - 100.

If there are 5 students in each group with grades randomly assigned, what is the best approach to getting the top 3 students (the top 80%) based on their grade?

To be more concrete if I had the following:

Ronald, Group A, 84.5
George H, Group A, 82.3
Bill, Group A, 92.0
George W, Group A, 45.5
Barack, Group A, 85.0

I'd get back Ronald, Bill, and Barack. I'd also need to do this over other groups.