Benefit of Attempting Both groups.

Dear Friends,

Can anyone tell me what is the benefit of giving both groups

suppose the average % required to pass the final exams is 50% 

whereas minimum pass marks for each paper is 40

hence if i attempt for both groups and get marks 

for Example

1. FR=52

2. SFM=45

3. AUD=42

4. LAW=44

============Total =183 ( ie 183/4=46%)

5. MICS=56

6. COST=57

7. DT=58

8. INDT=54

===========Total=225 (225/4=56%)

Both Total=225+183=408/8=51% 

It means average is look on total marks or group wise.

Please Guide.