I attempted gmat in Oct end 2013 and got 610 (QA-49, VA-25).. I had not competed all the Mgmat mocks. I was left with 2 of them.

Since then I have been preparing harder and have started taking mock tests. Below are the results

1. Gmatprep test 1 - 610 QA-49, VA-25 ( small disruption of power cut had occurred gmatprep doesnt save the incomplete test)

2. Mgmat test 5 - 650 QA-44, VA- 35

3.

Veritas prep free test - 730 QA- 50, VA- 40

4. 800Score free quant test - QA- 42

5.

Kaplan free test - 690 QA-50, VA - 28

All the tests are taken with a one day gap. I am confused by this huge variation and variable difficulty of these tests. Can anyone tell me whats going on?