Dumi, I tried adding "tone" by adding a sentence at the end of the essay.
Sorry about the delay.... there's so much to do here :D
Okkkkkkkkk... as I said before, you've already got a good framework; you have all the points that this answer should contain. But you tend to make statements where you can tell them through your own experiences that add more emotions and creativity to your writing and also make those guys convinced about your genuineness.For example;
This was undoubtedly a challenge since I had to cultivate the patience to work on a simple math problem for 15 minutes.
.... this you can say;
She needed more than fifteen minutes to solve a very basic math problem and I still remember how my patience was put on test. However ,... (now tell what you learned from this experience)
Also, I find this link may be helpful for you to further improve your answer;
//collegeapps.about.com/od/essays/qt/short-answer-essay.htm
You've already done a good job!
Good Luck!