Fun fact, your score will not change no matter what legal move you enter for #9 (well, maybe, read my next post)
I dislike the scoring for some of the others. I feel like sometimes the first move is guessable while the followup is sometimes difficult to calculate. Also some puzzles give partial credit... but when all the reasonable looking moves give at least some credit what's the point?
I remember taking this many years ago and getting 180xx. This time I got 2020, reviewed my answers, changed one, and got 2100.
A much better estimate is playing on a website like chess.com 
http://www.chessmaniac.com/ELORating/ELO_Chess_Rating.shtml
Mine is 1965, two years ago was 1690.