Ravi, You are right I passed my Certification for Plant maintenance with 81 %.What I did studied manuals 8-10 times and practiced exercises on DEV server frequently.The exam was totally from manuals & exercises.Some questions can be answered just by reading manuals while others are not possible to answer without practice on IDES.
Some questions were scenario based like Work Centre Capacit Calculations & preventive maintenance.Which can only be answered if you understand the input & output of System along with algorithms.
Thanks,
waqas