Helo!
I just took roun-up and got 35 out of 36. That is just about same that I was having before the exam. When I started to prepare to exam, some two months ago, I got constantly something around 90%. When I got first time here, half a year ago, I was between
cow chip and hood ornament but occasionally even silver spur.
During preparation I used RHE e-Trainer where I got results not qualifying ( no less than 50% ever, however ) but some, say two weeks before the exam, I was doing 90%.
Now I was concentrating on one or two medias to test myself. I randomly took some mock and failed drastically ( hopefully no more, or I'll sue 'em

) Whatta heck? I was doing just great on roundup and e-trainer!
Now what I think is that you should run yourself as many different mocks as you can get but try to analyze and validate along. Whenever in doubt, try to:
1) figure out ( and proof @see #3 )
2) grab a book,
STUDY and _comprehend_
3) share/question your vision on some forum like this
So, summa summarum, testing yourself is good thing but should be used only mean to be prepared. But yet, the score 70 does not sound very promising...
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Antti Barck
It Solutions Consultant -- NSD Oy Sun Certified Programmer for the Java™ 2 Platform