Grad_mba,
To put it in simple terms, the score depends on the level of difficulty of questions that you got right and wrong. Although you got 17 of the questions wrong, you got the tough questions right about 50% of a time.
Let's say you got a 700 level question #1 right, the CAT algorithm gave you a 800 level question next, and you got it wrong. Now it gave you a 730 question as a question #3, and you answered it correctly, so the next question you got was say level 750, etc. GMAT is trying to zero in on your ability level, and as long as you answer 50% of 700 level questions right, you will get a high quant score. The further down the test you get, the smaller is the range in difficulty of questions you are going to see. That's why 7 questions that you got wrong at the end didn't mess up your score too much. This has been discussed many times before, and even you dig into stickies on the forum or even search the forum, you will see a way more detailed explanations of how GMAT CAT scoring works.
Good luck!