MBA Entrance Exam

Yes, SBI PO and CAT preparation can go hand in hand.
Take a look at CAT syllabus:
CAT Syllabus - Complete Details of Quantitative Aptitude, Data Interpretation, Logical Reasoning, Verbal Aptitude, and Reading Comprehension
Here goes the details about SBI syllabus:
The topics in the second image have to be prepared isolated for SBI PO.
The general awareness topics mentioned for SBI would not suffice for CAT. GK knowledge for an MBA aspirant needs to be way higher than SBI PO.
SBI PO 2016 syllabus and pattern:
Take a deep understanding on CAT and SBI pattern and the possible number of questions under every topic. Prepare hard for CAT you would be able to crack SBI PO, excluding the technical part.
Wish you all success.

Sorry to say that you have no option to calculate your percentile score because percentile score is depend on -
1) Total no of candidate can appearing in the exam.
2) Number of candidates who have scored less marks than you.
Both are unknown to you, so you do not have to calculate it. Because this information is hidden to candidate.
If you collect above two date, then you can easily calculate your percentile.
From below given mathematical calculation, you can calculate your MAT percentile.
If N is the Total number of candidates appearing in MAT Exam
Then the percentile score P is given as,
P = (Number of candidates who have scored less marks than you/ N) x 100
So, in this process you can easily calculate your percentile.
I guess your percentile would be below 81.09 percentile.
All the best.