I'm not in the top 10 percentile of my class or top 20 percentile of my class, due to decisions I have made.
.... why you give two sets of percentiles? It does not make much sense to me... :(I am not one of the top ten students in my class due to certain decision I have made.
Since I took the entrance exam I had been anticipating a letter of rejection but instead I found a new sense of confidence in the letter.
What's the connection between the entrance exam and your anticipation of rejection... that's not very clear :(... instead I found a new sense of confidence in me
... you felt confident and may be the letter gave you confidence.