Here's the tl;dr on how to read the diagnostic
- The areas where the bar is to the left are areas where the examinee needs to improve their study
- Focus more so on the subjects that have a higher number of items, and lower performance score, in this case that means: hydraulics open channel, and then everything else
- don't worry about the cut score, or what one scored on the last attempt. The more time spent analyzing the diagnostic, the less time is spent studying things that will actually help pass the test.
Good Luck on your next attempt. If you can qualify to sit for the exam, you have the skills to pass it. Go kick its ass next time!
and the longer version:
See items 1,2 above
The cut score is not 70%. It hasn't been 70% in decades. The cut score varies between offerings and exam discipline. For the P&P exam, the cut score was rarely as high as 70% or a touch higher, it was usually under 70%. I strongly suspect the CBT cut scores are in line with P&P.
Do not try to predict the cut score! You need to
study as if the cut score is 100%. To prepare for less than 100% is to prepare to fail.
If you walk out of the exam feeling like you got 75% or higher, then you are probably fine.
Can one divine their score from the diagnostic? Yes, or at least get pretty close.
Is it a simple calculation? lol, no.
Can one figure out the cut score from the diagnostic? No, not really, maybe within +/- 5, but that's not really instructive
Am I going to elaborate on any of this: Nope.
Is the diagnostic confusing? Absolutely.
Can it be improved? Depends on how one defines "improved"? There are a lot of conflicting requirements placed on the diagnostic. The previous formats were even less instructive to examinees. The current form is simultaneously too simple and too advanced. If one focuses on points 1,2,3 above, then it's not that bad. However the audience are, by their nature, inquisitive and analytical, so the present format is at times more of a distraction than a benefit.